SDS200 Display

[Alain]

Good day all,

I'm currently monitoring a 700 MHz, P25, Phase1 system in the City of San Diego. Most transmissions show the signal strength meter go from 3 through 5 bars. Sufficient to monitor a majority of the signals.

Underneath the date and time display, is the usual P25, LINK, DATA, ENC, SLOT1-2 notifications. The problem?

During some transmissions, the display does NOT show any of these at all, even though signal strength shows a 5 bar signal.

I get no audio, no P25, LINK, DATA, etc. in the display area...nothing(!) However, the display is active & shows P25 etc., whenever I do receive the City of San Diego Fire/EMT/PD signals. Most confusing.

I turn to you for some clarity, please. All supposition, conjecture and hypothesis are welcome!

Many thanks for taking the time to respond!

 

[Saint]

ENC means it's encrypted you will not hear any audio
Steve

 

[Alain]

Steve said: "ENC means it's encrypted you will not hear any audio."

Steve, thanks for the reply. Yes, I know that no audio accompanies ENC signals.

I guess I didn't make myself clear here. Permit me to reiterate...

Wondering why it is that I receive NO audio on some comms in the clear. I get 5 bars on an in-the-clear transmission, but no indicator [P25, LINK, DATA, SLOT1/2] under the date and time!

 

[Saint]

Sorry can't think of an answer, but someone will probably chime in soon.
Steve

 

[tvengr]

You might try the wide invert or invert filters. Every system is different. You can try all of the filters to see which one works best. Are you having problems with particular talkgroups? If so, which ones?

 

[Alain]

tvenger, it happens when I use "ID searching". At times, an "unknown" TGID will display, and sometimes nothing is displayed, but the 5-bar signal strength will display.

 

[werinshades]

Wondering why it is that I receive NO audio on some comms in the clear. I get 5 bars on an in-the-clear transmission, but no indicator [P25, LINK, DATA, SLOT1/2] under the date and time!

How do you know if the comms are "in the clear" if you can't receive any audio? If you hold on the channel and you see ENCY in the display next to the P25 indicator, like it was mentioned it's encrypted.

 

[Alain]

werinshades said: "How do you know if the comms are "in the clear" if you can't receive any audio?"

Because, the very few encripted TGID's I do have, all show their TGID's during an ID SCAN; the indicator "ENC" shows up, right under the time and date...why would other ENC channels [found during an ID SEARCH] be any different??

Please correct me [and explain] if you believe I'm in error in my assumption.

Below is the link to the San Diego City db in RR in question.

San Diego City 700 MHz Trunking System, San Diego, California

San Diego City 700 MHz Trunking System Profile

www.radioreference.com

 

[werinshades]

werinshades said: "How do you know if the comms are "in the clear" if you can't receive any audio?"

Because, the very few encripted TGID's I do have, all show their TGID's during an ID SCAN; the indicator "ENC" shows up, right under the time and date...why would other ENC channels [found during an ID SEARCH] be any different??

Please correct me [and explain] if you believe I'm in error in my assumption.

Below is the link to the San Diego City db in RR in question.

San Diego City 700 MHz Trunking System, San Diego, California

San Diego City 700 MHz Trunking System Profile

www.radioreference.com

If I understand you're question correctly, you're asking why your display shows a P25/Slot/etc. indicator when it's receiving encrypted transmissions that you have saved in your talkgroup list, while during ID Search this information isn't showing? I would suspect because Uniden scanners are designed to "skip" over encrypted transmissions and/or the talk group might have both non-encrypted and encrypted transmissions. I've seen a few mentions of the dispatcher being in the clear while the units are not. Might want to put this question on the California forum for a better response.

 

[dougjgray]

I would speculate maybe there sending data that the scanner doesnt recognise or maybe when there are no radios connected to the sote maybe it sends a signal the scanner doesnt recogize, i see that on a couple sites on the colorado p25 but usually the scanner doesnt stay on those sites long

 

[maus92]

If the "bars" are fluctuating from 3-5 when monitoring a P25 simulcast system, you are basically in a fringe reception area, and reception will be degraded at times - at least that has been my experience. Fluctuating bars on a non-SDS scanner usually indicates signal problems associated with "simulcast distortion." I would put the radio in analyze mode, and look at the S and Q bars. If either are undulating or markedly low, your signal (RSSI and / or decode) quality is likely the issue.

 

[Alain]

maus said: "...Fluctuating bars on a non-SDS scanner usually indicates signal problems..."

Same applies with my SDS200?? I've use the same discone/LMR 400 combination since 2005 on my 996t and n-e-v-e-r had any signal problems. Our City of San Diego is broadcasting on [700 Mhz] SIMULCAST now, rather than the traditional sites prior to.

That change has made a dramatic [read: less-than-ideal] change in reception, I fear :-<

 

[maus92]

maus said: "...Fluctuating bars on a non-SDS scanner usually indicates signal problems..."

Same applies with my SDS200?? I've use the same discone/LMR 400 combination since 2005 on my 996t and n-e-v-e-r had any signal problems. Our City of San Diego is broadcasting on [700 Mhz] SIMULCAST now, rather than the traditional sites prior to.

That change has made a dramatic [read: less-than-ideal] change in reception, I fear :-<

I'm not sure how far away you are from the nearest tower site, but have you tried receiving with just the stock antenna? You may also be experiencing interference from a nearby cell tower.

 

[Alain]

We are in the country, near the Mt. Palomar Observatory, up about 2,500', and we are about 10 miles northeast from the closest cell tower. In addition, we have a 100' high hill in between the City of San Diego and my home. We are about 50 miles N/E from downtown San Diego. However, as I said, these "challenges" have had no impact on my scanning for the past 22 years---up until now! The 800 system came in loud and clear...this "simulcast" system, not so much.

 

[maus92]

We are in the country, near the Mt. Palomar Observatory, up about 2,500', and we are about 10 miles northeast from the closest cell tower. In addition, we have a 100' high hill in between the City of San Diego and my home. We are about 50 miles N/E from downtown San Diego. However, as I said, these "challenges" have had no impact on my scanning for the past 22 years---up until now! The 800 system came in loud and clear...this "simulcast" system, not so much.

Modern - particularly 700MHz simulcast systems are designed to keep their signaling within the intended jurisdiction, more or less, for frequency efficiency / reuse. Liberal use of directional antennas and downtilt.

 

[Alain]

maus, I'm in a really sweet spot, the 700 Mhz system notwithstanding.

I can monitor Bakersfield CHP, Santa Barbara CHP which are over 200 miles and 160 miles respectively. I can still monitor my local fire and sheriff et.al., so if I miss an occasional call from San Diego City fire, I'm O.K. with that.

I want to thank everyone for their input and time to post!

 

[maus92]

Also note that individual P25 simulcast tower sites are designed to have roughly an 8 - 12 mile range for on-street coverage.

 

[darkness975]

We are in the country, near the Mt. Palomar Observatory, up about 2,500', and we are about 10 miles northeast from the closest cell tower. In addition, we have a 100' high hill in between the City of San Diego and my home. We are about 50 miles N/E from downtown San Diego. However, as I said, these "challenges" have had no impact on my scanning for the past 22 years---up until now! The 800 system came in loud and clear...this "simulcast" system, not so much.

Modern - particularly 700MHz simulcast systems are designed to keep their signaling within the intended jurisdiction, more or less, for frequency efficiency / reuse. Liberal use of directional antennas and downtilt.

@Alain I would second this. The old 800Mhz SmartZone system that my state PD used to be on seemed to track a lot better than their new system.

 

[maus92]

@Alain I would second this. The old 800Mhz SmartZone system that my state PD used to be on seemed to track a lot better than their new system.

"Old" 800 SmartZone systems boom. The SmartZone system in my county was the first one installed in the state. It was upgraded about 10 years ago, doubling the original number of sites from 5 to 10. Back then, the design philosophy to ensure coverage was to install high gain antennas way up on tall towers and blast away. I could sometimes receive a usable signal 2 counties distant. The new 800 Astro P25 replacement system will have 22 sites, with antennas generally mounted lower, and directional antennas on border sites.