Transmission of call letters

[spiders24]

My Fire Dept dispatcher transmits the call letters at the beginning of every dispatch as well at the end. I’ve listened to other Dept's that only do this during the daily test. What is required? Can they just do it at the end of the Dispatch or is it required at the beginning as well?

 

[Russell]

That may come from the days when every base transmitter had to have individual callsigns and these callsigns had to be used at the beginning and end of each conversation (not transmission). This especially affected FDs as each station (base not mobile) had their own transmitter and sometimes these FDs just used these as their station identifiers.

Generally, the requirement has changed to 'system' callsigns and the operator can pick every 'conversation' or every half hour. Dallas FD uses one callsign for all transmitters in the 'system'. Now the stations just identify themselves by Station number where they used to use individual callsigns. Now the dispatcher just uses the 'system' callsign at the end of the exchange. With automated dispatch the callsign is transmitted as morse code every half hour.

Russell

 

[UFEMTFF]

In my area, I know of at least 3 UHF or VHF stations that do not identify their stations at all. 3 or 4 others use morse code every 1/2 hour or so. One county identifies itself at the end of every page out, verbally listing the station ID.

I guess the FCC has bigger fish to fry than unidentified stations?

 

[kb2vxa]

The requirement is every 30 minutes which dispatchers can't be bothered with so most have installed CWID modules. FYI the maximum permitted speed is 20WPM, I guess the FCC guys can't copy as well as hams. (;->)

Right, the FCC has bigger fish to fry, primarily the worst offenders of all, the broadcast industry. It ain't easy with severely limited manpower, usually only two field engineers working as a team for each district and there are ten of them.

 

[UFEMTFF]

Sorry to get this further off topic, but real quick, what is the policy with TRS?

I'd imagine they have a specific TG that is speccifically for airing the call sign, and it just cycles through all 28 or however many frequencies and airs the call sign.

 

[brandon]

On trunking I hear the CWID but only when scanning in conventional mode.

Funny thing is one of the local departments in San Diego County still voices their old VHF callsign on the TRS. Old habits I guess

 

[Jay911]

Sorry to get this further off topic, but real quick, what is the policy with TRS?

I'd imagine they have a specific TG that is speccifically for airing the call sign, and it just cycles through all 28 or however many frequencies and airs the call sign.

My city's system runs CWID on one freq per tower site and it does not go out over the trunk. The freq may not even be in the trunk rotation, I'm not 100% sure.

 

[zz0468]

One agency I worked for received an FCC waiver to identify once per hour using only the agency name, not the call letters. That's because with a dozen or more sites, all with different callsigns, it would have become cumbersome. The waiver came back with specific language for the voice id... "xxx Sheriff's Dispatch".

As far as id'ing trunkers, one channel in the lineup gets a cwid. The system will flag the id'er as a busy so it doesn't get assigned until the id is complete.

 

[nd5y]

There are different station ID requirements for different types of stations in different services.
The part 90 private land mobile services have three station identification sections. (90.425, 90.647, 90.735)
http://www.access.gpo.gov/nara/cfr/waisidx_06/47cfr90_06.html

 

[ibagli]

That may come from the days when every base transmitter had to have individual callsigns and these callsigns had to be used at the beginning and end of each conversation (not transmission). This especially affected FDs as each station (base not mobile) had their own transmitter and sometimes these FDs just used these as their station identifiers.

It's still that way in my county for the rural departments. The stations almost never identify using their station numbers or names, and some have made their station and truck numbers the same as their callsign. (When the county started moving from every station having Engine 1, Medic 8, etc., several went with the last 3 digits of their callsign as their station number. KNHZ390's stations 1 and 2 became stations 391 and 392.)

 

[N1508J]

Interference ????

My city's system runs CWID on one freq per tower site and it does not go out over the trunk. The freq may not even be in the trunk rotation, I'm not 100% sure.

Makes it kinda hard to locate the source of intermod, co-channel, image or other kinds of interference when a system ID's on only one assigned freq of many.

 

[Jay911]

Industry Canada tends not to license multiple users to frequencies, at least in my area and in my experience, so that (locating the source of interference on a single frequency) isn't really a concern. Furthermore, as others have mentioned in the thread between my first reply and yours, this is the norm for trunk systems.

 

[DiGiTaLD]

Station Identification

My Fire Dept dispatcher transmits the call letters at the beginning of every dispatch as well at the end. I’ve listened to other Dept's that only do this during the daily test. What is required? Can they just do it at the end of the Dispatch or is it required at the beginning as well?

Per Part 90 of the FCC Rules and Regulations, the callsign must be transmitted at the end of each of a running series of transmissions, or, for public safety licensees, every 30 minutes of continuous use. For business licensees, the callsign must be transmitted at the end of a running series of transmissions, or ever 15 minutes of continuous use.

Trunking systems identify themselves. Some conventional repeaters do, some don't. It just depends on how they are programmed. Nowadays, at least around here, it seems that most, if not all users of conventional systems have forgotten entirely about the FCC requirement to identify, as I hardly ever hear callsigns anymore.

 

[zz0468]

Makes it kinda hard to locate the source of intermod, co-channel, image or other kinds of interference when a system ID's on only one assigned freq of many.

It's not as difficult as you might think. co-channel and adjacent channel stuff can be identified by FCC records. If, for example, 867.8125 is only licensed at 5 sites in a 50 mile radius, it's a relatively easy matter to narrow down which one it is. In the case of an intermod mix, it's likely coming from a nearby site. Listening to the traffic on the channel provides clues, too. I've chased LOTS of interference, and never was the lack of an id anything more than a minor nuisance. Having the ability to df the offending signal more than makes up for not immediatly knowing who it belongs to.

 

[slicerwizard]

FYI the maximum permitted speed is 20WPM, I guess the FCC guys can't copy as well as hams.

Get a grip. That speed restriction has nothing to do with the abilities of FCC personnel.

 

[N4DES]

Sorry to get this further off topic, but real quick, what is the policy with TRS?

I'd imagine they have a specific TG that is speccifically for airing the call sign, and it just cycles through all 28 or however many frequencies and airs the call sign.

Trunking systems are required to send the CWID only on the "lowest frequency" of the channels assiged to a specific callsign every 30 minutes.

We have 4 callsigns assigned to the PBCTRS and a mix of 806 and 821MHz. channels. This results in 2 callsigns transmitted on the lowest 806 and 821 frequency at all 10 simulcast sites.

Here is thr FCC Rule:

http://a257.g.akamaitech.net/7/257/...ccess.gpo.gov/cfr_2006/octqtr/47cfr90.647.htm

 

[pogbobo]

fwiw around these parts its a mix of cwid, call sign by voice, and nothing ... and then some more nothing .... i dont know how they get away with it haha ... they probably have some agreement that i dont know about ...

 

[Russell]

Most CWIDs are transmitted without the PL/DPL tones so the users don't even hear it. If you have the PL/DPL tones set on your scanner you will also not hear it.

 

[wlmr]

Trunking systems are required to send the CWID only on the "lowest frequency" of the channels assiged to a specific callsign every 30 minutes.

We have 4 callsigns assigned to the PBCTRS and a mix of 806 and 821MHz. channels. This results in 2 callsigns transmitted on the lowest 806 and 821 frequency at all 10 simulcast sites.

Here is thr FCC Rule:

http://a257.g.akamaitech.net/7/257/...ccess.gpo.gov/cfr_2006/octqtr/47cfr90.647.htm

Even the requirement to ID on the lowest frequency doesn't need to be followed if the trunking system identifies itself in a manner that can be monitored. (Section C of the part 90 rules you posted the link to.) I've used PRO96COM on a P-25 trunking system and every half hour the data stream sends the call sign as well as indicating that one of the trunk frequencies (fourth from highest frequency) is transmitting the call sign. The way they interpret the rules is that identifying using analog morse code isn't even necessary but do it anyway, just not on the lowest freq. It's the only thing done in analog for this system, everything else is P-25 digital only.

It does seem that the frequency that transmits the call sign is last in line to be assigned voice traffic so that may be why an earlier post is noting the freq doesn't seem to be part of the trunked site. Appears that even the alternate control channels will be assigned to carry voice before the "ID channel".

Unlike someone's earlier post, on this system if the system is IDing and all the other channels are in use the system will stop the ID process until the voice traffic is done and then try identifying again.

 

[N4DES]

True - but there aren't many deployed that do that as there are more analog systems out there that only ID on the lowest frequency. As time marches on and pure P25 systems are deployed that will be the case, but currently Section B rules.

Also the frequencies that are assigned as the BSID are like the reserve control channels and are one of the last to be assigned in an analog TRS.