I only hear one side and beeping on the other

[proquist96]

On some conventional analog channels i hear talking on one side, and a steady low pitch beep on the other, sounds like a trash truck backing up. I can tell that someone is talking (during the beep) by the response of the person i can hear. Its not a trunked system. Could it be that the signal is too weak to get both sides?

 

[902]

On some conventional analog channels i hear talking on one side, and a steady low pitch beep on the other, sounds like a trash truck backing up. I can tell that someone is talking (during the beep) by the response of the person i can hear. Its not a trunked system. Could it be that the signal is too weak to get both sides?

There were some semi-duplex radio systems where the dispatcher spoke on one channel and the mobile spoke on the other so that the dispatcher always had control of the channel and the mobiles could not speak directly to each other. When the mobiles were talking to the dispatcher, the base would transmit beeps so that the other cars would know someone is talking to the dispatcher, but still couldn't hear the other car talking. The logic of doing something like that defies me, but agencies have done it.

That's what I think you are hearing.

I think years ago the CHP did something like this, but I'm not sure if they still do.

The other thing that does something similar is a CSI Model 9800 telephone interconnect. When someone makes a phone interconnect, the unit can be programmed to beep out when a mobile is talking, but will stop beeping and pass audio when the mobile stops transmitting. This is to make the interconnection a little more private (yeah, really).

 

[proquist96]

Thanks for clearing that up. John p.s. the CHP in my area i hear both sides fine thank goodness. Another question, why does the chp use such a low freq. its like 39.- 42.mhz analog its so much different than the police yet they still can communicate on the Red channel which is digital 860.mhz. Maybe a repeater converts it? For me to hear chp good i need to change antennas maybe i should use my pro 2026 only for chp with the loaded whip fully extended.

 

[zz0468]

Thanks for clearing that up. John p.s. the CHP in my area i hear both sides fine thank goodness. Another question, why does the chp use such a low freq. its like 39.- 42.mhz analog its so much different than the police yet they still can communicate on the Red channel which is digital 860.mhz. Maybe a repeater converts it? For me to hear chp good i need to change antennas maybe i should use my pro 2026 only for chp with the loaded whip fully extended.

There are several reasons why the CHP could still be on low band. They've been there since God was a boy, and it's expensive to change a statewide system. They may be happy with the coverage they get on low band - it's easier and less expensive to cover the state with a low band network than it is on 800. I know they've done experiments operating on several county systems on 800, and they always seem to go back to low band. Also, state wide frequency allocations in California are virtually impossible to be had in this day and age. What they have now is a valuable resource that's nearly irreplaceable. A CHP unit operating out of San Diego could, in theory, move to Yreka and talk. This is doable on other bands, but without the state wide frequency assignments they now have, it would be much more difficult - especially with the large number of discrete 800 systems that would be required to provide equivalent coverage.

I don't have direct knowledge as to just why they never changed, but those are probably factors in a much more complex situation.

As far as a cross band repeater, that's one way it could be done. Another is to provide the CHP units with an 800 MHz mobile radio, in addition to the low band radio already there. This has been done in several southern California counties.

 

[WayneH]

On some conventional analog channels i hear talking on one side, and a steady low pitch beep on the other, sounds like a trash truck backing up. I can tell that someone is talking (during the beep) by the response of the person i can hear. Its not a trunked system. Could it be that the signal is too weak to get both sides?

Since you say CHP is local to you are you talking about Los Angeles Sheriff's? If so, check out the California Forum. There's been talk about it in the past. Do a search of the forum and you'll find the explanation why (I don't recall).

 

[RolnCode3]

*snip*and you'll find the explanation why (I don't recall).

Because that's the way they've always done it. (according to the answers given in those discussions) It started out as a legit need...now, it's done because they've always done it.

 

[mciupa]

Because that's the way they've always done it. (according to the answers given in those discussions) It started out as a legit need...now, it's done because they've always done it.

Please don't ever change . When the tropo gods smile on us, we love monitoring CHP up here in the Northeast !

 

[RolnCode3]

Please don't ever change . When the tropo gods smile on us, we love monitoring CHP up here in the Northeast !

CHP staying on lowband is no problem...be a long time before that changes. (be nice if all of the mobiles were repeated across the base...for all of the dispatch centers, not just some...but that's a different discussion).

The "it's always been that way" comment was for LASD. They're the ones with the beeping on the output while someone talks on the input.

 

[902]

I came back from a conference in California a few weeks ago where the low band situation was mentioned. The problem is that there is a very large radio system that is effectively as large as Maine to South Carolina. The expenses involved in changing would not be impossible, but would be very high. That's the same problem other lowband systems face.

Balance that with the lack of availability of competitive bid equipment (Daniels seems to be the only base station available today, and they are not high power), rising noisefloor, trash from poorly shielded microprocessors in consumer and industrial equipment and impending BPL interference up to 80 MHz and many venues who still run lowband are hard considering leaving.

This may be a market engineered transition; Motorola discontinued all lowband base stations after the Micor product. In the 90's, they were drop shipping Glenayre base stations. Today, the only thing they can make is a Radius mobile with a power supply. The only M/A-Com base I've seen on lowband is an Orion mobile with a power supply. But these factors drive any decision to stay or leave the band.

 

[gcgrotz]

What about Tait Electronics in New Zealand? Do they make lowband stuff?

Lowband also has advantages in hilly terrain and will usually require fewer base stations than 800.

We used to hear Orange County fire on 46.46 here in VA when the band would open. Sometimes even the mobiles.

 

[DickH]

CHP staying on lowband is no problem...be a long time before that changes. (be nice if all of the mobiles were repeated across the base...for all of the dispatch centers, not just some...but that's a different discussion).

The "it's always been that way" comment was for LASD. They're the ones with the beeping on the output while someone talks on the input.

They may stay on low band until some fancy radio salesman gets into the state house and tells them how those freqs are going to be lost soon, they can't make that antique equipment anymore, can't get parts anymore, can't have interoperability, etc., etc., etc. The state reps will eat that up and do all the groundwork before anyone who knows anything gets wind of it, then it will be too late.
There are numerous examples of it all around the country.

 

[WayneH]

They may stay on low band until some fancy radio salesman gets into the state house and tells them how those freqs are going to be lost soon, they can't make that antique equipment anymore, can't get parts anymore, can't have interoperability, etc., etc., etc. The state reps will eat that up and do all the groundwork before anyone who knows anything gets wind of it, then it will be too late.
There are numerous examples of it all around the country.

Considering this is the State of California a salesman like that wouldn't fly. They've investigated and done studies multiple times. They know their limits and what's becoming obsolete. The old "you're behind the times, you need to install a trunked system" line won't hold weight here.

If there was a decent lowband station still made they could probably continue a bit longer considering Kenwood is still actively manufacturing the 690 (though it isn't as wideband as the Rangr). I *think* the M/A Com Orion is still being made in low-band also, and wideband at that. They did/do make a remote base model (I have one) but I'm not sure what the duty cycle is like.

 

[hogcat]

CHP radio history

Heres a link that gives a good history of the CHPs radios with pictures.
http://www.mbay.net/~wb6nvh/chpradio.htm

 

[FireRescueMedic11]

doesn't /\/\ make HT1250's in lowband?....covering the state of california with complete interops would cost Hundre$ of million$, and i couldn't see them on an organized trunked system, it would take years to develoup a complete system and talkgroups and a fall back just incase, also costing not only for the equipment, but the time and effort to make such a large state interop, i could imagine the system itself would be insanly huge, but who knows, computers come out and become obsolete in 15 days of rolling off the assembly line, so who knows what they want to do with their system,

 

[902]

doesn't /\/\ make HT1250's in lowband?....covering the state of california with complete interops would cost Hundre$ of million$, and i couldn't see them on an organized trunked system, it would take years to develoup a complete system and talkgroups and a fall back just incase, also costing not only for the equipment, but the time and effort to make such a large state interop, i could imagine the system itself would be insanly huge, but who knows, computers come out and become obsolete in 15 days of rolling off the assembly line, so who knows what they want to do with their system,

They do, but the problem with lowband portables is antenna and groundplane efficiency, as well as the constant detuning of the antenna when in proximity to different materials (metal from a car, concrete from buildings, being inside a structure, etc.). This is why there is less money invested in placing many receivers around for reliable portable reception (portable reception on lowband will never be 'reliable' to 95%/ 95%/ 95% public safety standards) and more money invested in high band portables with MO3 vehicular repeaters.

 

[902]

They may stay on low band until some fancy radio salesman gets into the state house and tells them how those freqs are going to be lost soon, they can't make that antique equipment anymore, can't get parts anymore, can't have interoperability, etc., etc., etc. The state reps will eat that up and do all the groundwork before anyone who knows anything gets wind of it, then it will be too late.
There are numerous examples of it all around the country.

My apologies in advance for disagreeing, but I think your statement minimizes the issue. There is legitimately a lack of variety in base station equipment and domestically-owned subscriber units. There is legitimately a severe problem with lowband noisefloor given everything these days has a microprocessor in it and those are unintentional RF emitters. In some environments, even mobiles are trashed by stray RF. BPL is a looming issue, particularly in rural areas where lowband has the greatest benefit. The thing I didn't mention in my earlier posts is that frequencies are shared and must be coordinated from state to state so that aberrant propagation (great for scannerists, very bad for the public safety user) is minimized. This means that talkpaths are limited to what is available. That may or may not be adequate for the agency, but it restricts the agency severely if resources are inadequate for their needs. These things are real.

In another thread elsewhere in the forum, someone mentioned that a trooper only needs the radio to tell their dispatch when they are leaving the vehicle to take a p**s. That may have been the case in the oldern days, but these days, young officers entering the job expect the technical means to perform their jobs and we are lagging far behind in providing those resources. Lowband can't accommodate the burgeoning need for technology for our newest generation of officers to be effective against the newest generation of bad guys.

I do agree with you that some manufacturers have resorted to end-run and carpetbagging tactics, particularly in light of federal funding. We seem to fritter away these funds on completely stupid s**t and do not build things that truly solve any of the problems that may exist.

"Interoperability" is meaningless if there is no "operability" first.