Frederick County, MD

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rvyingling

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Westminster
I am programming a BCD996XT for the Taneytown fire station. I have an account with Radio Reference as well. I programmed the scanner using the programming cable with Carroll County, Frederick County, Adams County & York County. Everything works except for Frederick... I programmed the P25 system but it says it can't find the control channel.... The firehouse is located approximately 5 miles from the tower at the county line.

Any assistance, suggestions are welcome, thanks!
 

ka3jjz

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I'm going to assume this is the system you're programming...

Frederick County (Project 25) Trunking System, Frederick, Maryland - Scanner Frequencies

You should have both the blue (secondary) and red (primary) frequencies programmed. If the primary shuts down and they start using one the secondary channels that you don't have, you will lose that trunk, and get that message.

If, however, you have both the red and blue frequencies programmed and still can't get it, there's a chance they've allocated one of the freqs listed in the db as a voice channel as a control channel. To find out, program ALL of the frequencies (in a P25 system, Unidens force the scanner into control channel only mode). When you find the frequency, please submit it to the database so it can be added.

You didn't mention anything about the antenna you're using...? HTH...Mike
 

rvyingling

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Westminster
I have tried it both ways regarding the frequencies... As for the antenna I connected to the external antenna located on top of the hose tower ( I have no idea what type it is) I also tried the telescopic antenna as well. The scanner is located in the radio room in the middle of a concrete & steel building. I have the same scanner in my truck on a small external antenna & it works well when I am working at Taneytown.

I work again Monday & I will try relocating the scanner to different areas of the firehouse using the telescopic antenna....

I spoke to a friend who works for DFRS & he told me many people who are close to the towers are having issues... The firehouse is 5-6 miles from the Bridgeport tower.....

Thanks!
 

PanhandleScan

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Jefferson Co. WV
PRO96 - WIN96 Programming for Fred. Co. MD P25

I have a PRO96 (and 2096) using Win96 software. I can't pick anything up with all freq's loaded into a bank. Am I missing something? How should I set my custom tables? Should I choose MOT3600CC, or MOT9600CC? Should I choose Custom Table or Multi-Table. Do I choose 800mHz Rebanded, or 800Mhz?
If so, what are the steps and offsets I need to use?

Thanks for your help.
 

craigg

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Oct 23, 2003
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Problems

I had successfully listened to Frederick County both prior to and since rebanding on my Uniden BC296D.

Since September, I have put the new frequencies in and have no luck catching anything at all. I can only get it on this website's live feed...

I have put all frequencies in... Red and Blue and Black; control, alternate control, and voice. I have activated the digital card...

I live just outside fort Detrick and nothing. Apparently, I am doing something dreadfully wrong...

When the radio was rebanded, I had to enter a new Rebanding Table (Band Plan, Base Freq (lower and upper) Offset, Polarity, and Spacing... then I had to refer to the bank as either Type 1 or 2 Custom... Again, I am no whiz but apparently did this successfully.

Now nothing... Any help is appreciated.
 

ka3jjz

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If the new P25 system Frederick is now using is also using LSM modulation, you may well be SOL. We now have a fair amount of experience with LSM in Maryland - Baltimore city and county as well as PG county - that suggests that the current crop of trunktrackers simply can't deal with LSM very well, particularly where there's more than one tower being received at the same time. In some cases, at least, you need to run some attenuation if this is the case.

I present this only as a possibility - not a real answer. But it does seem like there's at least some possibility of this here, as the symptoms all seem to be the same...Mike
 

freqhopping

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Lo Co VA/ FM19
When the radio was rebanded, I had to enter a new Rebanding Table (Band Plan, Base Freq (lower and upper) Offset, Polarity, and Spacing... then I had to refer to the bank as either Type 1 or 2 Custom... Again, I am no whiz but apparently did this successfully.

None of this matters now since they switched to the new system. You need to program a completely different band plan since it is not a Type II system.

Try this:
Base / Spacing
851.00625 / 6.25
762.00625 / 6.25
 

MrQRO

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Charles Town, WV
FredCoMD - NewP25System

I have to tell you this system stinks! Yeah it's LSM-Simulcast, but I've never seen worse coverage!

I have a Uniden 996 in a mobile w/ an external antenna, and I come up 270 and can only get a decent lock
on the control chnl once I'm over the "scenic overlook", and lose it once I'm past Jefferson on Rt 340.

I don't know how the public service folks are dealing with this system on one poor site, And the Bruswick
site, furgetaboutit...

That's probably why you're not getting them where you are.

What did they tell Moto., give us 1 site for the county @ 25 watts?
 

gesucks

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Our Nation's capitol
I have to tell you this system stinks! Yeah it's LSM-Simulcast, but I've never seen worse coverage!

I have a Uniden 996 in a mobile w/ an external antenna, and I come up 270 and can only get a decent lock
on the control chnl once I'm over the "scenic overlook", and lose it once I'm past Jefferson on Rt 340.

I don't know how the public service folks are dealing with this system on one poor site, And the Bruswick
site, furgetaboutit...

That's probably why you're not getting them where you are.

What did they tell Moto., give us 1 site for the county @ 25 watts?

No they are just using true P25 radios designed for LSM operation instead of a scanner that is not designed to be able to do LSM.
 

freqhopping

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Lo Co VA/ FM19
What benefit, if any, is there to using LSM rather than C4FM (and H-DQPSK for the TDMA) like Loudoun?
Frederick's license shows the emission designator for C4FM.

Is Frederick a case of C4FM for the subscriber units, but LSM for the sites?
 

jmarkey

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Dec 18, 2010
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Location
Frederick, MD
On September 12th Frederick County switched to a 12-channel Motorola P25 Phase I digital simulcast system, which uses linear simulcast modulation (LSM) using CQPSK/C4FM. The best scanning success has been found by managing how much you are asking the scanner to do, and how much signal gets in to the scanner (how many simulcast sites can be heard). This is somewhat counter-intuitive for many who think adding gain will help get clearer reception. With LSM most people inside the county do not have too little signal strength, their scanner can hear too many sites and the scanner front-end can't deal with it.

craigg:
Since you have your P25 card enabled already, I suggest you remove everything but the primary and alternate control channels (854.9875 is the primary CC) and use control-channel trunking. The data on RR regarding frequencies and talkgroups is right on. You may want to check your firmware version regarding any need to adjust for rebanding. I'm not familiar with your particular scanner.

If the new P25 system Frederick is now using is also using LSM modulation, you may well be SOL. We now have a fair amount of experience with LSM in Maryland - Baltimore city and county as well as PG county - that suggests that the current crop of trunktrackers simply can't deal with LSM very well, particularly where there's more than one tower being received at the same time. In some cases, at least, you need to run some attenuation if this is the case.

I present this only as a possibility - not a real answer. But it does seem like there's at least some possibility of this here, as the symptoms all seem to be the same...Mike

I have to tell you this system stinks! Yeah it's LSM-Simulcast, but I've never seen worse coverage!

I have a Uniden 996 in a mobile w/ an external antenna, and I come up 270 and can only get a decent lock
on the control chnl once I'm over the "scenic overlook", and lose it once I'm past Jefferson on Rt 340.

I don't know how the public service folks are dealing with this system on one poor site, And the Bruswick
site, furgetaboutit...

That's probably why you're not getting them where you are.

What did they tell Moto., give us 1 site for the county @ 25 watts?

No they are just using true P25 radios designed for LSM operation instead of a scanner that is not designed to be able to do LSM.

What benefit, if any, is there to using LSM rather than C4FM (and H-DQPSK for the TDMA) like Loudoun?
Frederick's license shows the emission designator for C4FM.

Is Frederick a case of C4FM for the subscriber units, but LSM for the sites?


There are several explanations of "why use LSM?", but there are a few slides in this presentation that may help illustrate it well for all quickly and clearly. http://www.simulcastsolutions.com/userfiles/file/simulcastforums/motorola_simulcast_part4.pdf

Frederick's system is a seven-site system that covers 660 square miles. Coverage testing was performed in accordance with TIA TSB-88 by dividing the county into 4,308 0.4 x 0.4 mile square test grids (4,308 grids), 3,684 were accessible for testing (the majority of the inacessible grids are in the mountainous, undeveloped areas in the State and National parks), with 3,491 grids having successful tests. This is a pass rate of 94.7%.

This testing also had in-building and method-of-use signal losses added to the test kits in the following amounts: countywide 17dB; the triangular area between I-70 and I-270 21dB; and City of Frederick 33dB. Obviously, the performance of mobile radios (and scanners) will exceed the 94.7% figure above, if they can process the CQPSK signal. As ka3jjz correctly points out, scanners quite often can't do what the radio does.

ERP ranges from 140 to 380 watts on the FCC ULS site.
 

jmarkey

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Dec 18, 2010
Messages
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Location
Frederick, MD
Taneytown FD

rvyingling: I happened to be in the Taneytown area Monday with some test gear in tow. The station is about 3.5 miles miles out from the tower at a bearing of 291 degrees. Outside the building you have good signal strength and low bit error rate. In the middle of the building you might have marginal or inadequate signal strength if its a pretty dense building with steel roof. Depending on the antenna type/condition/cable-type/cable-length loss you might also have a lot of loss there. It might be worth having a radio shop (or in house resource if you have one) take a look at what you have and see if its up to the job.
 

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jmarkey

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Dec 18, 2010
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Location
Frederick, MD
I defer to those who have them personally, but many have mentioned that the PSR-800 performs well on both P25 Phase I and Phase II. The Unidens and basic RS just aren't doing well (not sure any scanner does) when there is a significant time delay between two (or more) strong signals reaching the receiver. Hopefully the scanner manufacturers will work it out.
 

craigg

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Oct 23, 2003
Messages
7
I was the guy at the beginning of the thread with an old digital Uniden BC 250D that could not receive LSM. I recently got a new GRE PSR-800 and things are going well. Thanks to the guys that gave me the information.

One question deals with Frederick City PD digital encryption; Previously on my 250, I was able to scan the 4 frequencies and get the PD. Yes, often times the signal was encrypted but many times it was not, especially from HQ outbound.

I am not able to get the unit to acknowledge the PD at all. The instructions say:

"... some talkgroups are encrypted; your PSR-800 will NOT decrypt these channels, However, it will tune to them if M36 (for Motorola) and EDACS Dig (for EDACS) are selected in settings. The EDACS Dig setting also allows your scanner to tune, but not decode, EDACS ProVoice talkgroups."

I have selected both enabled. FCPD is in the 400 Mhz range, plus it's obviously not dealing with talkgroups; is this reason neither Motorola or EDACS setting will make the radio stop like my old 250?

thanks
 
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