996xt Band Scope Function

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1hdrdr

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I am trying out the Band Scope function on my 996 XT . I looked at the manual about this function and I was wondering were I can get a little better info on this mode. I did not think the manual was to good at covering all of the functions of this mode.
 

Kennrth

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BCD996XT BANDSCOPE
The Band Scope Feature is very popular with amateur radio operators so I suspect that this is why they decided to put this feature in the BCD996XT. Unfortunately they do not have enough code in the firmware AND FRONT PANEL KEYS so as to make it easy to operate. Menu’s Menu’s Menu’s Yikes.
I could not get Band Scope working properly using Butels’a ARC XT Pro Software. I don’t think the people over there get it and Uniden did not document it very well.
What Uniden calls Band Scope is actually a simple spectrum analyzer and it appears to work very well. It can be used to make ruff measurements of electrical emissions in a screen room. I’m sure that was not their intention. First let me say I do not know the full limitations or specification of its capability because Uniden did not publish any data on it.
The Band Scope Sweeps IF (Intermediate Frequency Amplifier) is swept for energy detection in the spectrum. The bandwidth filter being used to pick up that energy is unknown again because it is not published. I would guess the bandwidth would be similar to the modulation with FM,WFM,NFM. Don’t confuse bandwidth for Steps or Sweep start and stop width. I also am not sure which IF they are using Sweeping 1st or 2nd , 3rd ? May be all depending what band you are in.
You need to spend a little time to set this radio up so band scope works predictably well. My observation shows band scope uses the frequency to sweep based on what you are scanning or searching at the time. A bit hap hazard. To gain better control, program some custom search frequencies in the custom section. Choose one or two to put aside for your bandscope work. You are allowed I think 10 custom searches. Each one assigned to front panel key 0-9. Make sure you keep them locked out or you will have mess on your hands. If they are not locked out the radio will during scan mode will find them and start a search on them which can be confusing. It is scan/search mode they talk about in the documentation. You need to assign the band scope mode to keys 1,2 or 3. Button 3 is highly recommended and may not be optional in the 396xt. These are two different settings (Custom Search settings and Bandscope Key Settings).
So now you have some Custom searches programmed in and assigned bansdcope operation to Key 3.
Running the bandscope continuously has very little utility so keep in mind you need to be able to know when to hold em. Hold is the key which is very important here.
It is very very important to keep you Sweep widths to less than 6M 6 Mhz wide for the band scope to be very useful. Also keep steps down to 5Khz for best resolution.
The purpose here is to find a hit in the spectrum, stop the sweep, Move the frequency marker over where the hit was a listen to possible activity.
You are bound to have false hit markers because of birdies in your radio. After a while you will learn where they are and avoid them. They are somewhat obvious because they will be unusually high in amplitude and never changing. Band Scope is very useful as you can see and it will not hang up like search mode does because of a dead carrier, noise or birdies. While band scope is sweeping the audio circuits are turned off.

Here is how you do it.
While in Scan Mode hit hold.
Now press VFO Knob (function mode) and immediately press Scan/Search Key
Quick Search? Menu is on the screen. Hit “.” Key for No
Rotate Vfo now through menu until Custom Search if highlighted then press E
You are now in custom search mode. At the bottom of the screen you may see a number or numbers.
These are the banks 0-9 custom search modes. By using the number keys turn the one on you want and shut off all the rest. Similar to Quick Keys But Dashes and asterisks are not displayed which can be confusing)Don’t worry if search is hung up do to noise.
Now Pess Vfo knob (function key) Then key # 3. Now you are in Band Scope mode for the custom search you programmed.
You will see the bandscope display shown in the user manual. If you do not then band scope is not set up for QK 3.
You should at this time make the following settings.
Choose / change center frequency
There are three settings - CF Center Frequency, SPN (Span), STP(Step)
Hit the period key – settings menu shows up at bottom of band scopes display. Will shut down after a few seconds if there is no activity. Continue hitting the period key tabs through the three settings. When on CF (CF Blinking) Hit E . Edit Center Freq page comes up. Enter freq for center directly using numeric keys using period as the decimal. When done press E .
Band Scope comes up with CF that you set.
Again hit the period key and band scope menu comes up. Continue pressing period until SPN is blinking. Rotate VFO for 6M – (do not hit E)
Continue the same for STP and set for 5Khz using turning VFO knob.
Now you should be sweeping at you center frequency + and – 3 Mhz. Total 6 Mhz.
If you see a hit – Press hold. Band Scope Sweep Stops.
Now Press VFO once and rotate the frequency marker over where the activity was. When there is activity it will break the squelch and you can hear what you saw and the frequency displayed is the marker freq so you know what freq you are listening to.
Once you get the hang of it you will find band scope very useful. And remember there are key board functions that can very useful here – like Reverse repeater find. And Quick Save.

Other Things to keep in mind. Your scanner should be programmed to use default modulation for the band in use. You can force a modulation change using the modulation function on the front panel keys.
The front panel functions are labeled by the associated number keys. To access the function press the function key the number key associated with that function.

Frequency Stepping. Frequency spacing in a particular band is an agreement between the services that use that band. It is not the law but a gentlemen’s agreement. And many bands do not strictly adhere to it. Especially hams who hate the ARRL and use the band legally but may not adhere to the ARRL’s advisory committee advice. Anytime you are doing a search it is a good idea to use the narrowest step mode. So you don’t miss anything in between. It is not problem free. There is a chance you will pick up activity but be off freq. If you are familiar with the band it would not be hard to figure which way to go up or down. If not you can program for a few 5 Khz up or down for the best audio. Keep in mind the higher you go up the band bigger the steps will be. The reason for this is because the higher bands are allowed more bandwidth by the FCC so the band plan guys need to so space users more.
Frequency Sweep. Should not be excessive because the freq marker will not have enough resolution to pick up the audio in Band scope mode when you hit hold and move the marker over the Hit. 6M I found works very well. In the higher bands wider bandwidths may be ok. Above 400mhz. 8Mhz may be ok.
Start stop freq mode works better in a real spectrum analyzer than in a bandscope setting. Best to use a center freq and sweep above and below that setting. A real spectrum analyzer uses more than 1 IF internally and If bands are easily seen on the screen do to base level changes. Can’t realy see that in bandscope mode.
One more note here. When you are in the frequency marker mode note you will see the modulation type displayed on the screen. This is for your convenience so you know what audio demodulation you are using. This is important so you should be properly picking up the audio in the proper modulation format.
The radio has default settings which are very reliable. I would use them. Unlike step settings the FCC is more strict on what mode is used in what band. But some bands are shared. Unfortunately Single sideband FM and SSB AM which is used in the ham bands and CB bands is not available in most scanners. There are other modulation modes as well that scanners generally do not have. Many modulation modes are for Data. Packet modes, Frequency shift keying etc Even good old Carrier full break Morse code. Scanners are meant mostly for audio listening anyway. Digital audio is becoming very popular as well. Which brings me to a couple more things.
I can’t be sure but I do not know if you can pick up digital voice in Bandscope (Freq marker mode). Since the radio is supposed to sense APCO25 maybe it will. But since I live in an area which is virtually all analog I have not verify this as of yet.
Amplitude of the hit is probably no very reliable as to how strong the signal is relatively speaking. The radio uses Gain Control for good listening. To get a better representation as to signal strength the Analog AGC should be turned Off. I don’t advise that for digital mode. Digital requires a higher level to keep the signal intelligible.

-. ..--- -- .- -.-.
N2MAC
Ken C.
 
D

DaveNF2G

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I could not get Band Scope working properly using Butels’a ARC XT Pro Software. I don’t think the people over there get it and Uniden did not document it very well.
YMMV. It works just fine for me with XT Pro.

What Uniden calls Band Scope is actually a simple spectrum analyzer and it appears to work very well. It can be used to make ruff measurements of electrical emissions in a screen room. I’m sure that was not their intention.
Please specify your definitions of "band scope" vs. "spectrum analyzer."

Uniden's Band Scope feature does exactly what I expect a band scope to do - detect and display rf energy within a band of frequencies.

Also, I find it very useful to run continuously for several hours, then identify previously unknown active frequencies. It is a more efficient way to find unknown activity than search mode and can do so unattended.

Frequency Stepping. Frequency spacing in a particular band is an agreement between the services that use that band. It is not the law but a gentlemen’s agreement.
This is only true in the ham bands. The FCC and NTIA only grant licenses for non-ham operation on designated center frequencies per their respective regulations.

Using the proper channel spacing minimizes attribution of activity to incorrect frequencies. Channel spacing can be problematic in certain parts of the VHF band because of overlapping allocations. There are two bandplan shifts around 154 MHz, and the marine and railroad bands overlap, so channel spacing appears to be erratic in the 161-163 MHz range.
 

1hdrdr

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Messages
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BCD996XT BANDSCOPE
The Band Scope Feature is very popular with amateur radio operators so I suspect that this is why they decided to put this feature in the BCD996XT. Unfortunately they do not have enough code in the firmware AND FRONT PANEL KEYS so as to make it easy to operate. Menu’s Menu’s Menu’s Yikes.
I could not get Band Scope working properly using Butels’a ARC XT Pro Software. I don’t think the people over there get it and Uniden did not document it very well.
What Uniden calls Band Scope is actually a simple spectrum analyzer and it appears to work very well. It can be used to make ruff measurements of electrical emissions in a screen room. I’m sure that was not their intention. First let me say I do not know the full limitations or specification of its capability because Uniden did not publish any data on it.
The Band Scope Sweeps IF (Intermediate Frequency Amplifier) is swept for energy detection in the spectrum. The bandwidth filter being used to pick up that energy is unknown again because it is not published. I would guess the bandwidth would be similar to the modulation with FM,WFM,NFM. Don’t confuse bandwidth for Steps or Sweep start and stop width. I also am not sure which IF they are using Sweeping 1st or 2nd , 3rd ? May be all depending what band you are in.
You need to spend a little time to set this radio up so band scope works predictably well. My observation shows band scope uses the frequency to sweep based on what you are scanning or searching at the time. A bit hap hazard. To gain better control, program some custom search frequencies in the custom section. Choose one or two to put aside for your bandscope work. You are allowed I think 10 custom searches. Each one assigned to front panel key 0-9. Make sure you keep them locked out or you will have mess on your hands. If they are not locked out the radio will during scan mode will find them and start a search on them which can be confusing. It is scan/search mode they talk about in the documentation. You need to assign the band scope mode to keys 1,2 or 3. Button 3 is highly recommended and may not be optional in the 396xt. These are two different settings (Custom Search settings and Bandscope Key Settings).
So now you have some Custom searches programmed in and assigned bansdcope operation to Key 3.
Running the bandscope continuously has very little utility so keep in mind you need to be able to know when to hold em. Hold is the key which is very important here.
It is very very important to keep you Sweep widths to less than 6M 6 Mhz wide for the band scope to be very useful. Also keep steps down to 5Khz for best resolution.
The purpose here is to find a hit in the spectrum, stop the sweep, Move the frequency marker over where the hit was a listen to possible activity.
You are bound to have false hit markers because of birdies in your radio. After a while you will learn where they are and avoid them. They are somewhat obvious because they will be unusually high in amplitude and never changing. Band Scope is very useful as you can see and it will not hang up like search mode does because of a dead carrier, noise or birdies. While band scope is sweeping the audio circuits are turned off.

Here is how you do it.
While in Scan Mode hit hold.
Now press VFO Knob (function mode) and immediately press Scan/Search Key
Quick Search? Menu is on the screen. Hit “.” Key for No
Rotate Vfo now through menu until Custom Search if highlighted then press E
You are now in custom search mode. At the bottom of the screen you may see a number or numbers.
These are the banks 0-9 custom search modes. By using the number keys turn the one on you want and shut off all the rest. Similar to Quick Keys But Dashes and asterisks are not displayed which can be confusing)Don’t worry if search is hung up do to noise.
Now Pess Vfo knob (function key) Then key # 3. Now you are in Band Scope mode for the custom search you programmed.
You will see the bandscope display shown in the user manual. If you do not then band scope is not set up for QK 3.
You should at this time make the following settings.
Choose / change center frequency
There are three settings - CF Center Frequency, SPN (Span), STP(Step)
Hit the period key – settings menu shows up at bottom of band scopes display. Will shut down after a few seconds if there is no activity. Continue hitting the period key tabs through the three settings. When on CF (CF Blinking) Hit E . Edit Center Freq page comes up. Enter freq for center directly using numeric keys using period as the decimal. When done press E .
Band Scope comes up with CF that you set.
Again hit the period key and band scope menu comes up. Continue pressing period until SPN is blinking. Rotate VFO for 6M – (do not hit E)
Continue the same for STP and set for 5Khz using turning VFO knob.
Now you should be sweeping at you center frequency + and – 3 Mhz. Total 6 Mhz.
If you see a hit – Press hold. Band Scope Sweep Stops.
Now Press VFO once and rotate the frequency marker over where the activity was. When there is activity it will break the squelch and you can hear what you saw and the frequency displayed is the marker freq so you know what freq you are listening to.
Once you get the hang of it you will find band scope very useful. And remember there are key board functions that can very useful here – like Reverse repeater find. And Quick Save.

Other Things to keep in mind. Your scanner should be programmed to use default modulation for the band in use. You can force a modulation change using the modulation function on the front panel keys.
The front panel functions are labeled by the associated number keys. To access the function press the function key the number key associated with that function.

Frequency Stepping. Frequency spacing in a particular band is an agreement between the services that use that band. It is not the law but a gentlemen’s agreement. And many bands do not strictly adhere to it. Especially hams who hate the ARRL and use the band legally but may not adhere to the ARRL’s advisory committee advice. Anytime you are doing a search it is a good idea to use the narrowest step mode. So you don’t miss anything in between. It is not problem free. There is a chance you will pick up activity but be off freq. If you are familiar with the band it would not be hard to figure which way to go up or down. If not you can program for a few 5 Khz up or down for the best audio. Keep in mind the higher you go up the band bigger the steps will be. The reason for this is because the higher bands are allowed more bandwidth by the FCC so the band plan guys need to so space users more.
Frequency Sweep. Should not be excessive because the freq marker will not have enough resolution to pick up the audio in Band scope mode when you hit hold and move the marker over the Hit. 6M I found works very well. In the higher bands wider bandwidths may be ok. Above 400mhz. 8Mhz may be ok.
Start stop freq mode works better in a real spectrum analyzer than in a bandscope setting. Best to use a center freq and sweep above and below that setting. A real spectrum analyzer uses more than 1 IF internally and If bands are easily seen on the screen do to base level changes. Can’t realy see that in bandscope mode.
One more note here. When you are in the frequency marker mode note you will see the modulation type displayed on the screen. This is for your convenience so you know what audio demodulation you are using. This is important so you should be properly picking up the audio in the proper modulation format.
The radio has default settings which are very reliable. I would use them. Unlike step settings the FCC is more strict on what mode is used in what band. But some bands are shared. Unfortunately Single sideband FM and SSB AM which is used in the ham bands and CB bands is not available in most scanners. There are other modulation modes as well that scanners generally do not have. Many modulation modes are for Data. Packet modes, Frequency shift keying etc Even good old Carrier full break Morse code. Scanners are meant mostly for audio listening anyway. Digital audio is becoming very popular as well. Which brings me to a couple more things.
I can’t be sure but I do not know if you can pick up digital voice in Bandscope (Freq marker mode). Since the radio is supposed to sense APCO25 maybe it will. But since I live in an area which is virtually all analog I have not verify this as of yet.
Amplitude of the hit is probably no very reliable as to how strong the signal is relatively speaking. The radio uses Gain Control for good listening. To get a better representation as to signal strength the Analog AGC should be turned Off. I don’t advise that for digital mode. Digital requires a higher level to keep the signal intelligible.

-. ..--- -- .- -.-.
N2MAC
Ken C.
Thanks Ken, I have played with it and it does work . What you told me is WAY more then Icould get out of Unidens manual. I think the band scope function is cool I just needed a little more detail on how to use it . Thanks, JAY
 

Kennrth

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In reply Dave Stark NF2G

Hi Dave,

I appreciate your reply in this thread. Let me try to be more explicit.

If you check the user manual for the BCD996XT you will find a graphic embedded in the manual showing you what the front panel display of the radio looks like when it is in BandScope mode. The Bandscope mode is embedded in the Firmware of BCD996XT radio not in ARC XT Pro. Unidens manual explains how it is a specialized kind of search mode provided in the BCD996XT firmware. Custom Search is also another kind of search mode provided in the radios firmware.

ARC XT PRO never puts the radio itself into Uniden’s defined Bandscope Mode in the radios Firmware. ARC XT Pro puts the radio into custom search mode and generates a graphic display. What ARC XT PRO does is set up a waterfall display with the Stop Start Step info you entered. Then via the rs232c port sends a request for the S meter data. It takes the S meter return data for each step in frequency and displays it in a relative amplitude format on the waterfall graph. This is how it functions. Yes in does work as you stated but in my opinion is very limited in function compared to the Bandscope mode available in the radios firmware..
I am disappointed in ARC XT Pro because I expected that they would have put the radio itself into Bandscope mode and use all of its very useful functions which are really nice. In my opinion not colorful as ARC XT PRO but far more useful as it provides many useful functions not available in ARC XT PRO.

I hope this clears up any confusion that I may have created in my last post. I am an electronic test engineer not a tech writer.

You requested
Please specify your definitions of "band scope" vs. "spectrum analyzer."

Now please be fair about this. These are not my definitions but are industry wide accepted adjectives defining measuring instruments which are somewhat non specific and therefor general discriptions of types of measuement instrumentation. .


Bandscope - Scans a defined frequency range in selectable steps and displays a graph of S Meter values (vertical axis) against frequency (horizontal axis).

A spectrum analyzer Usually, a limited spectrum instrument somewhere in the Audio to light band frequency spectrum. Measuring test instruments displays a power spectrum over a given frequency range,

An IF SPECTRUM DISPLAY - displays energy from the radios discriminator circuit.

A BandScope display or If Spectrum display is crude sub set variation of instrumentation known as a spectrum analyzer. A full blown spectrum analyzer used in electronics engineering is a measuring receiver that analyzes energy in a specified frequency band set by the operator. The input of the analyzer often is a calibrated 1 decibal per milliwatt at 50 ohm impedances so the display can show parabolic energy displays in real Power or db per Volt in real time. The display width is typically in frequency units per cm on the horizontal axis of the displayed grid. A more detailed explanation would be beyond the scope of a simple forum post.


You Quote me
Frequency Stepping. Frequency spacing in a particular band is an agreement between the services that use that band. It is not the law but a gentlemen’s agreement.

I except your clarification that this is primarily true for Ham bands and not generally true for most all other services. This is an important clarification since the FCC sets these rules. The services do lobby the FCC for band space and regulations that are advantageous to themselves but ultimately the FCC sets these rules. I am not an active Amateur Radio Operator, I assume you are since you hold an extra class license so you are more keenly aware of these issues . I haven’t been in the hobby for over 30 years but I still kept my tech license N2MAC. I’m like the plumber who has leaky pipes all over his house. I spend all day at work in the field so on my off time the last thing I want to do as a hobby is electronics or Ham Radio. LOL But I do like to have a scanner about.

By the way as a side note I have developed my own software using VB6.0 to control the BCD996XT via rs232c. I received the protocol via UPMAN Uniden Sales Rep’s direction on the firmware upgrade page provided by direction on the RR the forum. That was nice of them.
My software has a very different approach than Butel’s ARC XT or FreeScan. I did not try to duplicate what they have already did but compliment what is missing. For example I am using the Bandscope facilities in the firmware via the rs232 protocols..I can turn on/off all Quick keys with one click or decaded. I can make specific changes in the radios configuration without having to upload an entire configuration file.
And many more which are too numurous to mention in detail here.

One more criticism of ARC XT Pro. Take a look at FreeScan. Look at all the printer options and print preview. Very nice . I can print out just systems or systems with groups or everything. ARC XT Pro which cost me $62.50 and print options are non existent. There is no print view or options. ARC XT prints out everthing with no print preview. Oh well.

I cannot distribute my software because the compiler is licensed to my company. It would cost me $700 to acquire a license to distribute it. Also I would need to purchase a packaging software from MicroSoft which sets up the software for installation into Windows versions which puts it into the registry so it can be properly removed another $300 bills. It is a work in progress without documentation or help files. But I was thinking of distributing it in source code format when I’m done. .
Happy Scanning
 
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Kennrth

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One quick remark to Jay.
Read the section of the manual which shows you how to use the front panel keys. The Yellow labels under the keys are all the functions available when you are in the hold mode. All these functions are availble in Bandscope mode when you put it in the hold mode while in banscope. You can be very creative here. Problem is one mis step and you can get frustrated and lost. I know because it happens to me. I guess part of a tough learning curve. That is why I decided to develope my own software in visual basic so I don't have to deal with all this complexity over and over. Based on my experience the best thing to do is create your own test type proceedures in writing because there are so many sequence of keys and functions you can't remember them all. Especially if you put the radio down for awhile. Document everything for yourself.

Happy Scanning
 

bctrl1

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Messages
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Sorry, but I am confused.

Unfortunately Single sideband FM and SSB AM which is used in the ham bands and CB bands is not available in most scanners.
Can you elaborate a bit on Single sideband FM?


To get a better representation as to signal strength the Analog AGC should be turned Off. I don’t advise that for digital mode. Digital requires a higher level to keep the signal intelligible.
I was under the impression that the AGC in these scanners was on the audio side. How does this relate to signal level? Is the AGC control we have really controlling the RF or IF stages?


An IF SPECTRUM DISPLAY - displays energy from the radios discriminator circuit.
I would expect an IF spectrum display to show energy from the IF output of the receiver, not the discriminator.
 
D

DaveNF2G

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Kennrth:

Many thanks for the clarifications. I appreciate your taking the time to explore this feature and to document and share your findings. If I get any results on P25 sensing in Bandscope Mode, I will let you know.
 

ProScan

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In reply Dave Stark NF2G

I cannot distribute my software because the compiler is licensed to my company. It would cost me $700 to acquire a license to distribute it. Also I would need to purchase a packaging software from MicroSoft which sets up the software for installation into Windows versions which puts it into the registry so it can be properly removed another $300 bills. It is a work in progress without documentation or help files. But I was thinking of distributing it in source code format when I’m done. .
Happy Scanning
What? The .exe & .dll's generated by the compiler are yours and not governed by the compiler licensing.

For a setup program, take a look at Inno Setup
Inno Setup
 

Kennrth

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Response to bctrl ;


Single Sideband FM has been around for a long time and is a favorite mode of modulation used by the military for many years. Most consumer products are not capable of using this mode. SSB FM is a hybrid of SSB Amplitude modulation used to drive and FM transmitter. There are many modes of modulation that are not available commercially and are reserved for proprietary services. The military is notorious for special modes of modulation for security reasons. During the Viet Nam war the army was using this mode smack dab inside some of the ham bands for local ground communication to confuse the enemy. This hardware was never available to the public. I am not sure if ssb fm is legal to use in the Ham bands but I suspect if it is not encrypted it may be ok but may attract unwanted attention. Hams are allowed to do a lot of experimenting in some of the upper bands. Most are becoming obsolete because digital encryption is more secure. I’m not an active Ham.

SSB-FM systems use the Hilbert transform to generate a signal which is simultaneously amplitude and frequency modulated, both components being single-sideband.

See web sites here for explanation of SSB FM mode
Single-sideband FM - Patent 4542534

Narrow band, SSB, FM transmitter - US Patent 4625319 Claims

As to “An IF SPECTRUM DISPLAY - displays energy from the radios discriminator circuit.”

Many radio including scanners FM type is multiple if stages. The first if stage which is very wideband but maybe a high freq IF Stage. So by design, detecting the first IF through a wideband discriminator will yield wideband signals in the audio (easier to design and cheaper parts used in audio range) range when mixed with a sweeping oscillator will yield an IF spectrum display. Keep in mind there a different kind of discriminators so here it is used as a generic term. Taking the signal directly from the last stage of the IF requires more complex design so as to not load the IF or inject noise. A special kind of buffer mixer design is used which in FM terms is a special kind of discriminator. Scanners because of the expense do not generally have this circuitry embedded it the design.
The last discriminator on a scanner will give you an unmodified wideband signal that could be used to demodulate special kinds of signals where the internal demodulators on not designed to detect. Commonly used to detect Packet or FSK etc. This is probably what you are thinking of.
As to
“I was under the impression that the AGC in these scanners was on the audio side. How does this relate to signal level? Is the AGC control we have really controlling the RF or IF stages? “
.
All amplifiers especially have 3db gain or more are subject to going into oscillation. It’s physics. The output signal can get into the input stage and start regenerative feedback which will blow up the amplifier because it is an in band oscillation. The amplifier can also go into out of band oscillation in a high frequency mode called spurious oscillation. It may not cause the amp to blow but will consume energy making the amplifier overheat or inefficient. Amplifiers need to be controlled to prevent this from happening. Feedback circuits are used to control this from happening. They also use these control loops to control the gain of the amplifier. There are complex design issues in using these feedback loops. Incorrect design can cause the amplifier to go into oscillation. Delay timing and phasing of these loops is critical to prevent oscillation and distortion.
The rub is that the analog feedback must be associated to the type of signals used in the stage. A special kind off feedback sometimes called scale down or AGC loops can be used to control feedback gain control loops across different stages that are using different kind in signals being amplified. That means you can have a feedback loop from the audio section all the way back to the rf section if you want to do that. These are DC Voltage control loops where the Ac signal is detected and uses a dc converter to make a dc signal relative to the output signal. CPU designs use (AC to DC convertors) to control gain in the loop. The loop has to be measured against a standard dc reference to detect variations so the loop can be changed to make dynamic compensations. Properly designed AGC loops can be designed to control gain, dynamic range, Shut down amp during overload, And control timing to prevent low freq gain oscillations. The simple answer is AGC is used to control multiple stages of amplifiers in a large loop mode. Since it is DC controlled it is very resistant to amplifier oscillation. Multiple loops can be used even freq cross over loops which can change over all gain when different bands are used.

In the BCD996XT is CPU controlled which digitally controls dc agc which is adjustable in firmware. I am not familiar with the design so I have limited knowledge about its specifics. The audio pot is not in the analog or agc audio gain loop at all that much I know. When you turn the pot the cpu detects digital signals from the pot and adjusts gain accordingly. Volume can also programmed via the rs232 port by sending numeric data to the micro. . Digitally designed AGC control loops/ are used. As well as analog control loops including bias loops to control thermal run away. Much of this are inside IC’s themselves.
 
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Kennrth

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Reply to ProScan
As to

"What? The .exe & .dll's generated by the compiler are yours and not governed by the compiler licensing."

Where can I verify this? Calling MicroSoft- tell them I'm developing software on VB6 thats not licensed to me but someone else who does not know I using it for personal use. Yikes LoL

I am completely unaware of this and confused. In the license It says something about being ok to distribute exe if the compiler is licensed but not to me as long as I distribute in a way where the run time library is not installed in the exe but is called externally. So it only will run on another windows computer that has the run time library installed. That assumes VB6 is installed product having it on that machine. ???
When I was younger an broke and unmarried I could have cared less. The more you have to loss the bigger a target you become . So I’m a little cautious here.


This is legal advice is it not. Is there a lawyer out there that can expand on this.

Inno Looks good. A big thanks – Is it free of shareware on the download ?
Inno Does have some restriction but appears ok for me to use as long as I maintain the source code which protects both of us. And put a readable notice of copyright of source code. Meaning I did not rip off someone elses copyright source code.
Have you used it ?
Inno Setup License
==================

Except where otherwise noted, all of the documentation and software included
in the Inno Setup package is copyrighted by Jordan Russell.

Copyright (C) 1997-2010 Jordan Russell. All rights reserved.
Portions Copyright (C) 2000-2010 Martijn Laan. All rights reserved.

This software is provided "as-is," without any express or implied warranty.
In no event shall the author be held liable for any damages arising from the
use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter and redistribute it,
provided that the following conditions are met:

1. All redistributions of source code files must retain all copyright
notices that are currently in place, and this list of conditions without
modification.

2. All redistributions in binary form must retain all occurrences of the
above copyright notice and web site addresses that are currently in
place (for example, in the About boxes).

3. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software to
distribute a product, an acknowledgment in the product documentation
would be appreciated but is not required.

4. Modified versions in source or binary form must be plainly marked as
such, and must not be misrepresented as being the original software.

Microsofts license stipulations are not so simple to understand.
 
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ProScan

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Where can I verify this? Calling MicroSoft- tell them I'm developing software on VB6 thats not licensed to me but someone else who does not know I using it for personal use. Yikes LoL
An alternative is Microsoft vb .net express edition which is free in every sense of the word.
It includes a converter to convert vb6 source code to vb .net source code.

Inno Looks good. A big thanks – Is it free of shareware on the download ?
Inno Does have some restriction but appears ok for me to use as long as I maintain the source code which protects both of us. And put a readable notice of copyright of source code. Meaning I did not rip off someone elses copyright source code.
Have you used it ?
Yes. It does work well and never had a complant on the setup. I use it as the ProScan installer. I don't use to to write objects to the registry other then an application shortcut.

This if from the Inno Setup web page:
Is it really free of charge, even for commercial use?
Yes, it may be used completely free of charge, even when deploying commercial applications. However if you wish to show your appreciation and support its development you can make a donation.
 
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1hdrdr

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Messages
62
Thanks for all the responses on this topic.I have played around with this function a lot and have it figured out. It is a great tool to have when searching unknown freq spectrums.
 
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DaveNF2G

Guest
It sounds like "FM SSB" is what is more commonly referred to as ACSB - Amplitude Compandored Side Band.
 

Kennrth

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Messages
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Bay Shore Long Island NY
Reply to NF2G

Yes I think you may be right about this. It’s a matter of semantics as it is a variant of this method. The SSB FM the army was using is simpler . The army also used a ssb division multiples system in the field when transmitting army telephone signal across point to point where there were no telephone lines. What a mess that was. Division multiplex AM SSb on telephone line converted to crossband broadcast multichannel very narrow SSB FM and back again. Was not very clear or clean. This I was told about by my brother who was in the signal core in the army in the 60’s.

The Army’s SSB FM does not have the sophistication of today’s Amplitude Compandanded Sideband. ACSSB is seems to be superior to original FM SSB the army used. ACSSB has sub band locking or pilot tones so radios can connect and stay locked to each other. It is very good for low altitude satellite communications where Doppler shift would cripple simple SSB FM. ACSSB also has much better data transfer capability because of superior compression techniques. ACSSB is superior even in mobile communications because of its anti fading nature.
My guess is Amateur radio guys are using this mode too. I was checking out some AmSat sites on the web. But saw no mention of it. Seems a lot of the old Oscar transponders don’t have this capability. So AMSAT guys are home brewing tracking systems. Looks like they using software and freq shifting the radios to compensate for Doppler effects of low flying satellites. Invention is the mother of necessity. These guys are having fun.
There are so many kinds of modulation it’s hard to keep up with it. I ran into a guy in the submarine service who was explaining a kind of modulation I never heard of before. He called it wobblecom. They use an atomic clock reference signal which is very accurate and stable and synthesize it down to some VLF signal and wobble the freq to send encoded text. The freq wobble is very small it had to be expanded for a human ear to detect it. He couldn’t tell me more except that it was slower than Morse code. And could broadcast long distances under the ocean .
 
D

DaveNF2G

Guest
Wobble sounds like a very low and slow method of FM. Maybe inspired by whale songs.

ACSB/ACSSB does have a pilot tone. It was going to be the primary mode on 220 MHz when that band was reallocated to United Parcel Service in the 1980s. As you said, there were problems. Now the UPS 220 band is essentially abandoned as they went to other methods of communicating with their fleet. It is slowly being reallocated to other uses, but will never be returned to the amateur service.
 

kayleesdad

Member
Joined
Oct 22, 2007
Messages
623
Wow, I think i finally got the very basics of what kennrth was saying.

With the 396xt I program SR3 to "band scope" and set SR1 or SR2 to a custom search.

HOLD---FUNC--SR1 puts the 396xt into SR1 custom search (which is my Custom 1) and also opens up 0-9 custom searches for one touch access (even if locked out, apparently).

So I can then go to say Custom 8 by hitting number 8 (and closing Custon 1 by hitting number 1 to focus on Custom 8) and then hit HOLD somewhere of interest in that Custom 8, and then hit FUNC---SR3 and the band scope pops up centered for that frequency from Custom 8.

I think it was the HOLD key that was missing from other instruction sources that made me think my SR keys didn't work.

One small step for others.....one big step for me! In another year or two I might figure out some of the rest it.

Thanks for the insight kennrth!
 
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