[SDS200] No Voice Heard San Diego 700 Mhz

[Alain]

Hello All,

When I first purchased the rig [November, 2019] I could hear San Diego Fire/EMT/Police audio very well. I don't often monitor S.D. from my qth, but occasionally I do. The past month or so I have been unable to hear anything comms at all---not even SANITATION, which previously was a booming 5 bar signal.

I have a discone up about 30' on a mast, w/LMR400 coax. The RSSI swings between 60 and 116 dBm. Signal strength is between 4 and 5 bars...but no "P25" indicator on any TG signal, even after 5 minutes of monitoring a busy "central dispatch" TG.

Current filter setting is wide invert which brings in the best noise numbers. I've changed the filter settings, from one to another, with no joy.

Inyo County Fire comes in at 3 signal bars; that's 300+ miles away to the north, but I don't get a peep from San Diego, just 40 miles to the south.

Any ideas on where to point me? Where I might be going wrong, would be most gratefully received. Thx!

 

[jonwienke]

Your RSSI is swinging from the minimum to maximum values. Either you have a bad connection somewhere, or some really bad interference. Are you near a cell tower?

 

[Alain]

" Either you have a bad connection somewhere..."

Why would a bad connection single out San Diego 700 Mhz to go bad and nothing else?

Jon...I'm 10 miles S/W of the Mt. Palomar Observatory.

 

[jonwienke]

A couple of notes:
Holding on a talkgroup means nothing when monitoring a trunked system. The scanner will still scan multiple sites if you have more than one programmed and active, it will just ignore any traffic that doesn't match the held talkgroup ID. If you want to diagnose trouble receiving a site, turn on ID search and do a hold on the site, not a talkgroup.

Double check your programming is up to date. If frequency assignments have changed, you might be scanning the wrong thing now.

Bad connections can have frequency-dependent effects. Depending on where the bad connection is, it can affect some frequencies more than others. And if the bad connection is intermittent, it can be particularly troublesome to identify.

Interference might be an issue. 700MHz is adjacent to a cellular band, and you might be getting interference from a cell tower that comes and goes depending on call volume.

 

[Alain]

"A couple of notes:
Holding on a talkgroup means nothing when monitoring a trunked system. The scanner will still scan multiple sites if you have more than one programmed and active, it will just ignore any traffic that doesn't match the held talkgroup ID."

But...I'm not holding on a talkgroup. I'm speaking of the whole San Diego City 700 Mhz system.

"Double check your programming is up to date."

The system worked a month to 6 weeks ago; I've checked the RRDB and the San Diego 700 MHz systems remains as I have it programmed.

" Bad connections can have frequency-dependent effects."

You're speaking internally, in the scanner?

"...700MHz is adjacent to a cellular band, and you might be getting interference from a cell tower that comes and goes depending on call volume."

Jon...I'm miles away from any cell tower. I do thank you for taking the time to reply! You're the singular respondent, so I'm assuming that the other 171 who have glanced or read my post are as "in the dark" as we!

 

[hodad200]

also not picking up 700 mhz. switched over to 800mhz and everything is coming in clear.

 

[jonwienke]

You mentioned holding on a TG in post #1. Perhaps that's not what you meant, but it's what you said. And that's all I have to go on, not being psychic.

 

[inigo88]

@Alain the current control channel is 771.48125 MHz. Press channel, type it in, and channel again to direct enter the frequency, and see what you see. You should see “DATA” in the top right corner and P25 NAC: 370h flashing below the frequency.

99.9% of the time these issues are caused by the control channel not being programmed.

 

[es93546]

Inyo County Fire comes in at 3 signal bars; that's 300+ miles away to the north, but I don't get a peep from San Diego, just 40 miles to the south.

I assume you are picking something up on 153.8750. The City of San Diego is licensed for that frequency. It is more likely that you are picking that up. There is also a repeater on this frequency at UC Irvine. Inyo County has a repeater on this frequency on Mazourka Peak, northeast of Independence. To pick it up there would likely require some very uncommon ducting in the atmosphere during a limited time period. Keep in mind that discones have no gain. What traffic content leads you to think it was Inyo County Fire?

I'm curious as I live 40 miles north of Bishop and don't pick up Mazourka at all, except during one particular ducting event about 10-15 years ago. That was on ham radio, about 7-8 MHz lower in frequency.

*EDIT* If you pick up 153.8750 in San Diego County, 154.7250 (Inyo SO) should boom in at your location, among a few more.

 

[inigo88]

Yeah Inyo county from northern San Diego county seems pretty optimistic. I couldn’t even get Inyo county from the high desert when I lived there.

 

[Alain]

"I assume you are picking something up on 153.8750."

I'm not. At this moment I am monitoring 154.430 Mhz. Engine 5 and 52 are "...off Cottonwood at the I.C."...in Bishop, in Inyo County

 

[Alain]

"I assume you are picking something up on 153.8750."

I'm not. At this moment I am monitoring 154.430 Mhz. Engine 5 and 52 are "...off Cottonwood at the I.C."...in Bishop, in Inyo County...

 

[Alain]

@Alain the current control channel is 771.48125 MHz. Press channel, type it in, and channel again to direct enter the frequency, and see what you see. You should see “DATA” in the top right corner and P25 NAC: 370h flashing below the frequency.

99.9% of the time these issues are caused by the control channel not being programmed.

I have that cc in my 700 Mhz site programmed previously.

 

[Alain]

"To pick it up there would likely require some very uncommon ducting in the atmosphere during a limited time period."

I've lived here, at my current QTH for the past 22 years. I check into the Santa Barbara ARC and Bakersfield ARES nets during the week, with S-9 signals received and transmitted. Yes, it's even better from April thru June when tropo is in full bloom. I'm up over 2.200' elevation.

Not to put too fine a point on things, but I have spoken to the Bakersfield ARES net control op, who was in an AMTRAK train heading back to Bakersfield---stopped in Hanford---while he was on his H/T. Of course, he was utilizing the Breckenridge repeater at the time.

"I'm curious as I live 40 miles north of Bishop and don't pick up Mazourka at all, except during one particular ducting event about 10-15 years ago. That was on ham radio, about 7-8 MHz lower in frequency."

Maybe you should move to northern San Diego County...

 

[es93546]

"I assume you are picking something up on 153.8750."

I'm not. At this moment I am monitoring 154.430 Mhz. Engine 5 and 52 are "...off Cottonwood at the I.C."...in Bishop, in Inyo County

That is the Bishop Fire Department frequency. They have a repeater on Silver Peak, northeast of Bishop. They don't have an engine 52. They don't have a repeater on Cottonwood and they don't have a large incident going, where an I.C. (Incident Commander) is in charge. The Cottonwood repeater site is located between Lone Pine and Olancha and is only about 1/4 of the way up the eastern slope of the Sierra Nevada. It covers U.S. 395 from north of Lone Pine to Little Lake and the state highways around Owens Lake. I would consider it a low level repeater. Lone Pine has a repeater on 154.340 on top of Cerro Gordo peak or mountain, located east of Owens Lake.

I've been confined to the house at my desk all day due to heavy smoke from the Creek Fire. I've been monitoring 154.430 all day, with my scanner in the logging/recording mode. Since 1000, when I turned on the logging feature of the scanner, there have been 4 transmissions between 1136 and 1331 on the frequency. Nothing else since. I can pick up the repeater on Silver Peak with ease and pick up direct traffic from the Bishop PD dispatch center and occasionally some apparatus depending on their location in their fire district, which extends beyond the city in the Bishop Rural Fire District. The dispatch on this frequency identifies as "Bishop 2." Personnel identify with 100 series numbers. I'm not sure, but I don't think there are 5 engines on the department, which has 3 stations.

"To pick it up there would likely require some very uncommon ducting in the atmosphere during a limited time period."

I've lived here, at my current QTH for the past 22 years. I check into the Santa Barbara ARC and Bakersfield ARES nets during the week, with S-9 signals received and transmitted. Yes, it's even better from April thru June when tropo is in full bloom. I'm up over 2.200' elevation.

Not to put too fine a point on things, but I have spoken to the Bakersfield ARES net control op, who was in an AMTRAK train heading back to Bakersfield---stopped in Hanford---while he was on his H/T. Of course, he was utilizing the Breckenridge repeater at the time.

"I'm curious as I live 40 miles north of Bishop and don't pick up Mazourka at all, except during one particular ducting event about 10-15 years ago. That was on ham radio, about 7-8 MHz lower in frequency."

Maybe you should move to northern San Diego County...

I'm not going to move to any urban area, unless forced to due to health. I moved out of southern California in 1973 and have lived in somewhat remote rural areas since 1978. I lived in the big city of Flagstaff from 73-78. We were staying in Escondido in 2004, attending a couple of family events in San Marcos. The traffic was beyond imagination. My wife has a cousin and her husband in Fallbrook who live on the ridge above I-15. I let them do the driving when we visit right after Christmas. It is very stressful on us when we drive there after spending Christmas in Scottsdale. I've lived in Mono County for 39 years now, 32 of it in Mammoth. There are some 12-13,000 foot peaks between there and Mazourka Peak. The ducting was on a 146.760/146.160 repeater and I got in the first part of a transmission, but was unable to reply after someone replied to me. The reception lasted about 3-4 minutes.

I will take a look at who else in southern California is licensed on 154.4300.

 

[es93546]

"I assume you are picking something up on 153.8750."

I'm not. At this moment I am monitoring 154.430 Mhz. Engine 5 and 52 are "...off Cottonwood at the I.C."...in Bishop, in Inyo County

Closer to you there are 4 licensed users of 154.430, Fallbrook, San Marcos, the City of San Diego, North County FPD, a couple in Imperial County and a ton in L.A. County. I didn't check the Ventura County license. It is far more likely you are hearing one of these departments.

In the eastern Sierra 154.4300 can be used as a tactical when such use does not interfere with the Bishop FD. So there are licenses from Olancha to Independence and a few in Mono County. Only the June Lake FD uses it for a tactical all the time, and only when they are in the June Lake Loop, which is shielded from Silver Peak due to topography. Once they get out on U.S. 395 they can't use the frequency. All the other departments in both Inyo and Mono have licensed tacticals that are unique to them in this area of the state. 154.4300 used to be the dispatch frequency for all of Mono County, pre 911 system in about 1982 at the latest. It is also licensed to Carson City, NV. It might have been the only fire frequency in the eastern Sierra long back when.

 

[inigo88]

I have that cc in my 700 Mhz site programmed previously.

And what about direct entering the control channel and looking/listening for cc data like I said after? You’re on step 2, check the programming. I’m on step 1, check and make sure you still receive the system. Maybe the techs adjusted some sites? You’re definitely well outside their intended coverage area for the simulcast system. Direct entering the cc and verifying it still decodes will provide an easy answer to that question.

 

[Alain]

inigo88...

I followed your instructions in your post [#8].

Typed in the CC [771.48125] and yes, the "DATA" flashed [under the Oct 13 date]

Also the "P25" and the NAC 370h flashed below the frequency

Lastly, the RSSI moved from a low of -108 to -114. Signal strength was 2 - 3 bars.

The NOISE was all over the place: low of 775, high of 28110

Does any/all of the above info confirm your step 1 hypothesis?

 

[Anderegg]

You are right on the edge of being able to actually receive anything...at least by that rssi value. You said it worked previously then just stopped working...did you note the RSSI previously?

And BTW, when you see the RSSI go from basically no signal -116, to 60, that is typically an indication that the scanner is searching for control channels, and you are seeing CC list freq's being scanned, and their RSSI's being dispalyed...when tyou get control lock you get DATA on the display, and the D-ERROR display will also activate, assuming you have that on your display options as enabled. No ERROR display means your scanner is not locked onto, nor decoding the system.

Paul

 

[Alain]

Paul said: "... You said it worked previously then just stopped working...did you note the RSSI previously?"

No, I didn't make note of the previous RSSI. I never thought it to be necessary.

What would you suggest that I do next, Paul?