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Better but still not 100%

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Jphila20

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#1
I'm using two NooElec NESDR Smart 0.5ppm TCXO dongles.

Still having an issue with decoding the MARCS system in Lorain County, Ohio. Signal Health is 100, RSSI is 68 and window is 0. For voice RSSI is 65 and Window is 18.

Do I want a lower or higher number in the RSSI and Window?

Do I adjust the "Correction" to acheive this?

I have run DSDPlus in SDRSharp on specific frequencies within the site and I can decode with no problem.

Thanks.

Old Guy with New Technology.
 
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#2
Hi JP;

Your RSSI and Window numbers look good. If you can get 100% decode of the control channel, leave the gain settings as-is. You want a Window value as close to zero as possible.

The PPM correction value is a decimal number effective to the nearest 1/16th of a PPM. Like the window value, the PPM warp correction can be positive or negative.
 

Jphila20

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#3
DSD Plus & Trunker

Signal VCO will show a health value of 100 when the Voice is locked on a channel. Voice VCO - RSSI will drop to a few points either side of zero while displaying the source and target. Usually +5 or -5.

WhenDSD Plus is running I get a lot of “No Sync”, “TDULC” and “TSDU”.
When I get “LDUC1” or “LDUC2” I hear something coming out of the speakers, but it's not always audible. I don't know what these initals/letters indicate.

The event window doesn't change except for the time.

I tried to upload the short audio clip, but it errors out.

Can't sem to figure this out. Hate to be a pain in the .........

Thanks!

Old Guy with New Technology.
 

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SCPD

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#4
The window value on the voice role receiver is huge. Even when parked - it shouldn't be that far off zero. Also, the RSSI seems high for a park frequency that is likely dead air.

The signal role receiver looks pretty good.

Set the park frequency to 0.0000.
Set the squelch - on both receivers - to something that silences the audio when there's no signal present.

LDUC1 / LDUC2 are voice frames. TDULC marks the end of a conversation.

Please post an image of the voice role VCO 'Scope tab during an active call. You may need to tweek something in VB Cable.
 

Jphila20

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#5
Requested Pictures

I changed the Park to 000.0000 and Voice RSSI is 49 with Windows at 1 went no channel is active. Jumps to 67 with Window flucuates between -16 to +6. Still garbled or no voice. Squelch for both is set to "0". If I unmute signal and have the audio output to speakers I get the normal control channel sound.

I have included 2 pictures. One shows both scopes - left/signal and right/voice and the bottom is the DSD scope at the same time.

The second picture is the what appears when I first open DSD Plus.

Appreciate the quick response.

Thanks!

Old Guy with New Technology.
 

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KD8DVR

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#6
Signal VCO will show a health value of 100 when the Voice is locked on a channel. Voice VCO - RSSI will drop to a few points either side of zero while displaying the source and target. Usually +5 or -5.

WhenDSD Plus is running I get a lot of “No Sync”, “TDULC” and “TSDU”.
When I get “LDUC1” or “LDUC2” I hear something coming out of the speakers, but it's not always audible. I don't know what these initals/letters indicate.

The event window doesn't change except for the time.

I tried to upload the short audio clip, but it errors out.

Can't sem to figure this out. Hate to be a pain in the .........

Thanks!

Old Guy with New Technology.
You need to get a squelch value set for UT to get your ppm values set right. That's why you hear nothing. Your dongle us off frequency on your voice channel.

AntiSquid Disclaimer: All comments are personal opinion only and may not indicate a claim of actual fact.
 

Jphila20

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#8
Much Better

I found that the by changing the bit rate on the "Line 1" from 1 channel 16 bit 48000Hz to 2 channel 16 bit 32000Hz improved the audio by 85%. Most audio is now understandable. There are time when it sounds like a buzz, but usually only at the very beginning.

Since I made the change the DSD+ Event Log is running also.

Hope this helps anyone else new to this and THANKS again all the feedback.


Old Guy with New Technology
 

KD8DVR

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#9
I found that the by changing the bit rate on the "Line 1" from 1 channel 16 bit 48000Hz to 2 channel 16 bit 32000Hz improved the audio by 85%. Most audio is now understandable. There are time when it sounds like a buzz, but usually only at the very beginning.

Since I made the change the DSD+ Event Log is running also.

Hope this helps anyone else new to this and THANKS again all the feedback.


Old Guy with New Technology
I changed mine, too, for funsies. Too early to tell, so far... BUT, it didn't hurt :)
 

SCPD

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#10
You need to get a squelch value set for UT to get your ppm values set right. That's why you hear nothing. Your dongle us off frequency on your voice channel.
I thought so to but the OP also says:
Jphila20 said:
Voice VCO - RSSI will drop to a few points either side of zero while displaying the source and target. Usually +5 or -5.
RSSI doesn't go negative so OP must be referring to the Window value. +/- 5 is pretty good. OP later adds:
JPhila said:
Jumps to 67 with Window flucuates between -16 to +6.
So the warp value is keeping the voice RTL pretty close to center.

Compare the DSD+ scope waveform to the Voice VCO scope waveform. The VCO VCO waveform has some headroom. The DSD+ scope waveform runs right up to the edges of the window. Seems there is some gain in the VAC cable.

I suggest switching back to 48000 sps audio and reduce any gain added by the VAC.
 

Jphila20

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#11
If you are need of an antenna for 698-780mhz, 14dB, I found one one line for $24 including shipping. Its about the cost of building one, but probably better. I live 30 miles from a tower thats running at 852mhz and with it I get signal and some voice. I was using an HD TV antenna turned vertical and got nothing. I should note that th TV antenna works well for towers with in 15 to 20 miles with a 100 health reading when using Unitrunker. Just thought I'd pass it along.

YA70014F DMS Wireless 700 MHz Directional Yagi Antenna with 14.0dBi gain | eBay
 

Jphila20

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#12
High Negative Window Number

Can anyone explain this? Listening to Ohio MARCS and when the voice channel is parked the Window value will sky rocket to a very high negative number. (See attached.) When a voice channel is received it takes a while for the negative number to come back down and then only after the Window value drops into the teens negative or positive do I finally hear a voice. The voice park channel is close to the control channel.
Any suggestions?

Also, how do I clear attachments?
 

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GTR8000

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#13
The window is showing a large number because you are so close to the control channel. It "sees" the control channel signal in the adjacent spectrum, and calculates the window accordingly.

Do not park the voice receiver near any active frequencies. Find a very quiet frequency that has no activity on it, and leave it parked there. It doesn't have to be within the same band as what you're listening to, since it automatically tunes to the voice frequencies. You could set it to 50 MHz and it would still tune just fine.
 

GTR8000

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#14
Oh and also, you need to set a squelch value for the voice receiver, otherwise it's not going to function properly. Unitrunker already explained this in a previous post.

Set a squelch value that is slightly below the average RSSI of the voice channels. For your purposes, 55 should be fine.
 

Jphila20

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#15
Unitrunker stated:

Compare the DSD+ scope waveform to the Voice VCO scope waveform. The VCO VCO waveform has some headroom. The DSD+ scope waveform runs right up to the edges of the window. Seems there is some gain in the VAC cable.

I suggest switching back to 48000 sps audio and reduce any gain added by the VAC.


When I switch back to 48000 single I get no audio. If I choose any of the single channel - no audio. How do you adjust VAC gain? Using VAC 4.15.0.7313. Search "help" file for info on adjusting gain and couldn't find anything on it.
 
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#16

KD8DVR

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#17
Locate the Windows sound mixer. I can't be terribly specific because this varies by Windows version.

Right click on the Speaker icon in your task bar. You should be able to find you way to a window that looks like this:

https://bd23.https.cdn.softlayer.ne...images/virtual-audio-cable-default-device.png

Click on the "Recording" tab. There is usually a level adjustment there.
I've found, the level adjustments will not work. You need to use the mixer.

AntiSquid Disclaimer: All posted content is personal opinion only and may not imply fact or accusation.
 
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