DETROIT PD/FD Reception

[Microkid]

Is Anyone Who Is Located In The Northern Burbs Receiving Detroit PD/FD,( All Districts) FULL TIME?

If So.....Let Me Know What Equipment Your Are Using.....IE....Receiver/Ant. ETC.....I Get Chop & Coms Off & On

 

[tonya]

In Sterling Hts on 15 between mound and ryan and its hit and miss mostly miss. Even tried a diamond antenna with no luck. was in downtown also this week and reception was choppy.

 

[stack697]

Inside Detroit W/ Pro 96 my reception varies from very choppy to almost inaudible at times

 

[Combustion]

I believe Thunderbolt covered it all in this message which I have copied from another thread in the Michigan Forums and pasted here. I have taken the liberty to paste it in here because it is the most reasonable explaination of the possible technical nature of the problem that I have read. The problem appears to be unique to the subsystem, not to the scanner or antenna.

Brian

Quote:
Originally Posted by Thunderbolt
When the PRO-96 upgrade was released, and later the Uniden 796D, both scanners were supposed to be able to decode and track CQPSK simulcast systems. The actual demodulation testing was based on simulcast systems operating on the Twin Cities' ARMER TRS, which are in fact subsystems to main system. Likewise, the same testing was done on identical 9600 baud, 800 MHz simulcast systems in Arizona. Both comparison tests were a huge success and plans went forward from both GRE and Uniden to produce subsequent scanner models, such as the PRO-2096 and Uniden 396D, which so far have not had any problems with the aforementioned systems. However, we have three MPSCS simulcast subsystems that have come online in the past several months and we are pulling our hair out.

Michigan loves to test the latest in technology that is out, and it might be possible the data decoding firmware in our scanners needs an upgrade that allows for greater error correcting capabilities. Incidentally, none of the Detroit PD/FD or Wayne County Sheriff units have reported any reception problems like we are. This leads me to believe that GRE and Uniden will have to personally analyze our local systems, so they can build better scanners in the future that will not have these current problems. Especially, since narrowbanding will be coming along with 700 MHz to our state in a few years.

73's


Ron

 

[gpp10x]

Combustion; Thanks for posting that information from Thunderbird. I live 3 blocks from the city limits and have the same problem as everyone else. I hate the idea of buying a new radio & would prefer to wait until rebanding, narrowbanding & 700 MHz is completed before buying a new radio. Hopefully GRE & Uniden can & will fix the current problems with a firmware upgrade.

 

[marcp90]

If it will help we should all write a letter to Radio Shack addressing our compaints, and request that they develope an upadate for the DSP-App firmware to fix reception on the CQPSK sytems.

300 RadioShack Circle
Ft. Worth, TX 76102-1964
Attn: Customer Care

Phone: 817-415-3200
817-415-3240 (FAX)

http://www.radioshack.com/Contacts/CustomerRelations.asp?OID=1

 

[PMSCAN]

Marcp90 ... thanks for the link ... sent messsge requesting firmware upgrade. Will let everyone know if I hear anything

 

[Microkid]

I Also Sent A Message In Regards To This Dilema....

Just E-Mailed RS Customer Care.....Thanks For The Link.....

 

[marcp90]

Radio shack just replied to me. They asked for system ID's, my address, and proximity to the system.

 

[EC-7]

I'm guessing that its not a signal reception level problem, but a decode problem. I can hear the controll channel decent ~80-90% but when I run Pro96Com on the controll channle, it locks up the program trying to decode it. I have had a lot worse signal on othere MPSCS toweras and still decoded it fine, without having the software lock up. It locks up on 2 different computers, and ONLY on the Detroit system.

 

[mikey60]

I'm guessing that its not a signal reception level problem, but a decode problem. I can hear the controll channel decent ~80-90% but when I run Pro96Com on the controll channle, it locks up the program trying to decode it. I have had a lot worse signal on othere MPSCS toweras and still decoded it fine, without having the software lock up. It locks up on 2 different computers, and ONLY on the Detroit system.

I have no problems decoding the control channel on Pro96Com...

When I listen to the control channel from home, I will hear a solid signal one minute, then a few seconds later I'll hear some high pitched sqeaks in the background, followed by the control channel audio completely disappearing. To me it sounds like a phasing problem between the towers on the system, where perhaps one tower is not locked and synchronized with the others... Just my thought.

Mike

 

[tusker305]

ALL Units in the Detroit System are using 5 watt portable radios. Police,Fire and EMS.Very Few if any of the mobile radios have been installed in the rigs yet. (Just found out tonight). This may be why no body can recieve properly. It may not be the radios we are using, just more of the mayor's smoke & mirrors. Could the low power portables be causing the reception problems?

 

[EC-7]

Its not the type of radio tha there using, mobile or portable, because we dont listen to the individual radios themselves. We monitor the reoeater, that the mobiles talk on one freq, and the repeater spits the audio out on another freq. We *should* always have the same signal on the repeater tower, when it works right, where on a handheld direct, we would have a different signal on each radio.

A 5 watt handheld to handhed direct range at 5' off the ground, would only be about 2-5 miles. When you transmit to a 150' tower that repeats your transmissions with 100watts, you get 40+ miles. Also, I think there handhelds might only be 2 watts, but I'mnot positive.

 

[KB8UYC]

Its not the type of radio tha there using, mobile or portable, because we dont listen to the individual radios themselves. We monitor the reoeater, that the mobiles talk on one freq, and the repeater spits the audio out on another freq. We *should* always have the same signal on the repeater tower, when it works right, where on a handheld direct, we would have a different signal on each radio.

A 5 watt handheld to handhed direct range at 5' off the ground, would only be about 2-5 miles. When you transmit to a 150' tower that repeats your transmissions with 100watts, you get 40+ miles. Also, I think there handhelds might only be 2 watts, but I'mnot positive.

A 5 watt portable could be the problem. The portable coverage is not good at all and yes it could be why we are not hearing them as well. But the way the system is designed is another problem. Also there is no repeater on the towers except for I call and I tac. The regular MPSCS Omni Directional antennas are not repeatered.

Eric

 

[jsmeed]

A 5 watt portable could be the problem. The portable coverage is not good at all and yes it could be why we are not hearing them as well. But the way the system is designed is another problem. Also there is no repeater on the towers except for I call and I tac. The regular MPSCS Omni Directional antennas are not repeatered.

Eric

I doubt that the portables are the problem because dispatch is hit and miss as well. My experience has been that at the beginning of some transmissions, ERR=0 and then it deteriorates before it cuts in and out. I did seem to find an area around 8 Mile and I-75 where all comms were clear. Not sure, though, if I was lucky, or if the tower coverage is unique there.

 

[Mark01]

I doubt that the portables are the problem because dispatch is hit and miss as well. My experience has been that at the beginning of some transmissions, ERR=0 and then it deteriorates before it cuts in and out. I did seem to find an area around 8 Mile and I-75 where all comms were clear. Not sure, though, if I was lucky, or if the tower coverage is unique there.

Just a thought for the Detroit reception issue,but has it been confirmed that all the towers are up and running .After driving down the Lodge near Wayne State University today that area has a strong signal it's about 4 bars on the signal strength meter.The BCD396 I was using was recieving and decoding talkgroups with no problems.once you drive west past 6 mile the signal strength drops off and cuts in and out.

Mark

 

[rdale]

The system works very well for the users... This is the same issue that Monroe Co simulcast listeners have noted - but now that it hit the big city more are making noise! It is an issue with the scanners.

 

[Alpha432]

Question

Why is it that I can hear Detroit EMS Dispatch and some units pretty good and even some DPD units but I cannot hear Detroit Fire Dispatch on 8239 at all??

 

[EC-7]

A 5 watt portable could be the problem. The portable coverage is not good at all and yes it could be why we are not hearing them as well. But the way the system is designed is another problem. Also there is no repeater on the towers except for I call and I tac. The regular MPSCS Omni Directional antennas are not repeatered.
Eric

Well then could you please give me a logical explanation of how the system works?
The entire system is one large group of linked repeaters. There is NO way that it can be all be done simplex. If its not repeated, then explain how one radio can talk across the state and mulitple towers can retransmit the signal. The frequincies that RR database lists are all repeater output freq's. The radios themselves (portables, mobiles, bases) transmit 45Mhz lower than the freq we have programed into the scanner.

The towers controll channel constantly tells the radio what channel is available at that time to transmit on, so when the user keys up, the radio automaticly switches to that freq, and transmits. Then the towers control freq tells all the other radios on talkgroup XXXXX to switch to the output freq that is 45Mhz higher than portable or mobile radio is transmiting on and repeats the same audio out.

most public safety radios are on repeaters. You can definatly tell when the they are on simplex, cause all the radios will have a different signal strength. Its just kinda crazy to think that the MPSCS system is simplex and they use it without any repeaters, cause thats the way the entire system is setup and designed.

 

[jsmeed]

Detroit PD/FD Reception

Last night I took my scanner as I drove from Dearborn to Warren. I found that the caomms were clear as long as you were in the city and reasonably close to a tower. For example, all talkgroups were very clear (ERR <10) in Southwest Detroit as long as I was close to the Livernois tower. When I was in between towers, things would then tend to breakup and the ERR values would start to rise (30-40). When leaving the city limits (North on Van Dyke from 8 mile) the signal would start to fade fast. In fact, at 8 Mile and Mound, my 396T couldn't even lock on the control channel, even though within a quarter mile or so east or west everything seemed O.K.

Is it possible that we are just dealing with a relatively low power signal that confuses the scanner when it receives from more than one tower at a time? How does Motorola deal with this?