Help With M/A-Com P7100 IP

[DepSmith]

Greetings,

I had a question about the M/A-Com P7100 I am currently using in Patrol. Depending on the situation, I am having severe problems with my radio in conjunction with an Impact PTT Lapel Mic/Earpiece. When transmitting both my fellow deputies and my communications center are receiving massive amounts of squelch and feedback. I am looking into doing what I can to rectify the situation asap.

My first question, should you know the answer, do you know a solution off the top of your head?

Second, will a different antenna fix this issue by amplifying the signal strength?

Any help you can provide will be greatly appreciated. Officer safety is taking a big hit any time I hit the road with this current setup.

I don't know jack about radios, so the lingo is lost on me.

 

[Forts]

Does your department not have any radio guys (or a contract with a radio company) that might be able to help you out?

Couple things to help narrow it down... If you remove the lapel mike from the radio, and just use the radio itself... audio is ok? Are other officers using this same setup, and if so... can you swap lapel mics with one of them to try on your radio? Might be able to narrow it down a little bit at least...

 

[DepSmith]

We do have our own radio shop. Unfortunately when I took my radio into them they looked it over and ran it through a series of tests, of which I have no information regarding, and returned it to me saying it was in fine condition.

Without the lapel mic the radio works "ok" transmitting decently with still some feedback on the dispatch's end. However, fellow officers in the area still receive a decent amount of feedback when I transmit. I haven't attempted to use any other officer's accessories, however, I have another lapel mic and a shoulder mic, both of which offer the same issues.

 

[radioman2001]

I don't understand the feedback you are mentioning, unless there is another radio close by there shouldn't be any feedback. If there is another radio nearby, then that's the problem and not the radio or your lapel mic. If there is another radio, that one has to be turned down to prevent he feedback, then test the lapel mic. It's a common problem in all kinds of services. Does your department only use portables or are there mobiles installed also?
Oh BTW, using the lapel mic with a window open is an invitation for all kinds of back ground noises. Another possibility is if there is an amplifier in or with the lapel mic, it's gain may be set too high for a mobile enviroment. Meaning a lot of car introduced background noise.

 

[DepSmith]

I don't mean that kind of feedback. Like I said, my lingo is way off. It's a fuzz noise, scratching, kind of thing. I assumed it would be called feedback or squelch or something. But it's just like white noise.

 

[krokus]

Wirelessly posted (BlackBerry8530/5.0.0.973 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/105)

I assume that mic attaches to the side connector; have you tried a "regular" speaker-mic on that radio?

I'm wondering if there is one of the following wrong:
1) Bad connection (either in the cable, or at the connector)
2) Wrong type of mic element, for that type of radio.
3) Defective mic element.
4) Misadjusted or defective mic amp, inside the radio.
5) Mic is picking up excessive wind noise, possibly due to missing wind screen.

 

[jim202]

My question would be when you took it to the radio shop, did they test it with your speaker mic? I haven't tried poking into the software for that radio. Many of the radios today have the ability to adjust the external mic gain. It could be set too high.

Second comment would be that you have a dirty connection between the side of the radio and the connection on the speaker mice connector. Do not use an abrasive cleaning on these connections, but try to use a rough cloth to polish the connections. The gold plating is thin and can be taken off with things like a pencil eraser. Once the gold plating is gone, your in for a real problem all the time.

The other possibility is that you have a poor connection inside the radio and your not going to be able to fix that yourself.

It would be a good idea to try another mic that you know works OK on another radio. Play musical chairs and try to point the finger to a bad connection, bad speaker mic or a bad radio.

 

[DepSmith]

The gold plating is thin and can be taken off with things like a pencil eraser. Once the gold plating is gone, your in for a real problem all the time.

Is it possible that the mic could be screwed on too tight and could be bypassing the gold plating? I ask because the attachment has little gold prongs that stick into the side and appear to have possibly punctured the plating on the side.

 

[LMR_Dude]

External Mic Gain on the P7100's is set under OPTIONS>PORTABLE RADIO OPTIONS. The choices are Normal or High, the High setting boosts the gain of the mic by 10db.

Dep Smith, feedback is a high pitched squealing noise. It happens when then radio "hears" itself from another source when it is transmitting. On the new digital systems feedback sounds like an echo of the person thats gets usually progessively louder. In both cases, moving away from or turning down the volume on the other speaker makes the feedback stop.

I've never seen an Impact mic only Otto brand mics. Sometimes a wire will fracture, usually, in the molding above the connector and this leads to bad comm until the wire finally pulls apart and the mic dies. Swapping out he mic is your best step to isolate this problem.

The advice the other posters is the same I would given so I'll just add make sure the unit is clean (the mic element is small and it wont take much to block it) and be sure you are speaking into the mic.

 

[DepSmith]

Yes, I know what feedback is. I definitely used the wrong term. What I meant to say is when I transmit it comes through as majority static. And that's too dispatch, who has kickass radio equipment. To every other officer out there, they are hearing almost entirely static and nothing more from me.

Here's what I know:

First and foremost, it doesn't appear I have the ability to access the Options on my radio. So a radioshop may have to fix it if I only knew what to fix.

Today I attempted to use my typical shoulder mic: It's an Otto V2.
https://encrypted-tbn0.google.com/i...FjllAgkFRgVgI0ljTyac4u_i9mV2YlmxFkoW8CE3bXhDZ

This is the mic I have and would like to use, but is transmitting all static. It's a PTT Lapel Mic:
http://www.impactcomms.com/product_thumb.php?img=images/G2W-AT1-HW.jpg&w=435&h=291
Actual model - http://www.impactcomms.com/product_info.php?products_id=252

Hopefully those images work for ya'll. Now, as of today, my shoulder mic worked fine. I was able to hear and transmit clear as day. As of the day before, my PTT Lapel Mic still wasn't transmitting well. This would typically lead me to believe that it's a problem with my Mic, but this is the third I've had and find it hard to believe that three would fail, all in the same fashion. Therefore, I am trying to learn if it is something within my radio that is causing it NOT to work well with this type of mic.

The only real difference I can find, is the lack of an external antenna. Leading me to think the following: When the shoulder mic is in I believe that the original antenna is rendered un-used, forwarding the antenna usage to the antenna installed on the shoulder mic end. When a different form of mic is plugged into the same port, could it possibly be shutting down that same original antenna thinking there should be one installed on the mic [although there isn't] and therefore losing signal strength? Is that something that can be remedied?

If not, what other options might you be able to assume?

PS:
Also, the shoulder mic can only be screwed in so tight, as it uses a locking mechanism to attach. The PTT Lapel Mic does not use that same type of attachment. It utilizes a screw that can be tightened. Is it possible the attachment is being screwed in too tight and hurting the connection? Just spit balling on this one.

 

[LMR_Dude]

The condition that comes to mind is what I call "dead air". Your radio is is transmitting a signal powerful enough to reach your system but contains no voice, the other users are hearing only background noise.

I suspect either the microphone element in the lapel mic is bad or there is a broken wire/pin. Check the hieght of the pins in the lapel mic connector for uniformity. Also press on them and make sure they spring back to thier original positions. Wiggle them and see if one is looser than the others (I remove the rubber boot that pins protude thru to do this). Are there any cracks in connector housing?

Look at the UDC (Universal Data Connector) pads and you can see wear marks were the pins contact them. Are any of the wear marks on the fringes of the circles or on the plastic near the pads?

Are the tabs above the UDC, on the radio, that guide the lapel mic connector into postion worn?

About the External Antenna port in the UDC. Something has to press directly onto the center pin (brass colored) far enough to disconnect the radios antenna. Since your setup appears to be working now the pin should appear to be flush with the white insulating material. I have seen a lapel mic (without an external antenna) go screwy and disconnect the antenna knocking the radio out service.

I dont want to to turn this into a book but there are ALOT of things to look at.

 

[mm]

Lets start at the beginning again with some questions:

1. Does your OTTO V2 shoulder mic have an external antenna installed on it where it is up in the air and out in the open when you are transmitting, your V2 photo does not show an external antenna ?

2. If the OTTO V2 shoulder mic is indeed the model with with its own external antenna, is this the setup that works fine without any noise to dispatch ?

3. It looks like the impact lapel mic works thru an adapter that connects directly to your P7100's side interface connector (UDC) without any type of external antenna, if this is true then your impact lapel mic will then be using the antenna on the P7100 and you probably have the P7100 on your duty belt with its attached antenna touching your body, is this correct ?

If question # 3 is correct then with the impact lapel mic connected to your radio you will be transmitting with the antenna that is connected to the P7100 which is touching your body or close to it and probably lower than an antenna attached to a shoulder mic.

If the OTTO V2 public safety shoulder speaker mic with its external built in antenna is working fine and the impact headset is noisy when it uses the antenna on the P7100 then this sounds like the antenna connected to the P7100 is being shadowed/detuned by your body resulting in a degraded weak signal.

Is my understanding correct or do I have it backwards ?


Mike

 

[DepSmith]

1. Yes it does have an external antenna that shoots up over my shoulder touching nothing. That's my bad on the photo. Very much akin to: http://i278.photobucket.com/albums/kk99/USMC03_photos/03 Design Group-BCM/DPP_0015copy-3.jpg

2. This setup worked well last night and tonight. I was able to transmit sitting in the car and standing outside the car with minimal interference.

3. The impact lapel mic (ILM) works through the same adapter as the Otto. Only the ILM doesn't have an external antenna. Thus, I assume it uses the same antenna attached to my radio. However, it's odd because the ILM picks up everything being transmitted to me crystal clear, however, it's outbound is awful. Especially worse when I am sitting in my vehicle, about 50/50 when I am standing outside. The antenna on my radio does touch my side a little bit in the process.

I wasn't aware that if the antenna was touching me it would throw off the outbound transmission's signal ONLY. Is this something that could be remedied by a different antenna? IE - Do they make something more powerful? If all of this is the case, I need to know how to fix it.

 

[mm]

Your portable is only around 4 or 5 watts, the repeater that dispatch transmits to you an is probably around 45 to 100 watts.

The receive signal on your P7100 will be degraded by the same amount as your signal transmitted back to dispatch in levels that are called decibels or dB for short.

If your body or a poor location of your portables antenna inside the vehicle degrades your outgoing signal by lets say 3 dB then your transmit power is now only half of what your portable is capable of, (2 to 2.5watts) similarly the signal from dispatch that your P7100 receives is also degraded by the same amount in dB but since the dispatch repeater is initially 10 times stronger or greater, then your portable will still receive a useable strong signal from dispatch but the half power drop is most likely enough where your transmit signal is not useable on the other end anymore.

Unfortunately it comes down to whats called power margins, in base stations which run off of AC power they are capable of transmitting back to you at high power levels with considerable margins for fading signals and such.

With a portable radio you are limited by the battery power and by what's called MPE FCC regulations which limit you to around 5 watts maximum, and depending on the frequency band it may be closer to 2.5 watts max from a handheld, hence you have typically a negative power margin.

Additionally while operating inside of vehicles you typically experience another 10 db or greater reduction from the vehicles surrounding metal depending on the operating frequency.


The solution is that you need to get your portables antenna up and in the clear, there are other ways to do this if you want to use the impact setup and keep your portable on your duty belt and these come down to using whats called a MOBILE REPEATER which is located in your vehicle but this is complicated and may require you going to a different frequency band on your portable.


Mike

 

[mm]

Here's another suggestion that may work if you don't mind.

You could check and see if there is a public safety speaker mic, (PSSM) available with the audio accessory connector built in, it should also have the connector for the external antenna on it.

You would attach the PSSM to your lapel and then connect the IMPACT audio accessory to the PSSM and use the IMPACT mics built in PTT in place of the PTT on the PSSM.

I'm not sure if Harris or OTTO has this option available but it's worth a check.

This way the PSSM, which is only used to mount and hold the external antenna up in the clear, will enable you to still use the IMPACT's ear mic/speaker.


Basically you would have the OTTO or another brand Public Safety Speaker Mic, with its built in external antenna, mounted up on your lapel and connected to your P7100 which is on your belt.

Then your IMPACT EAR MIC is coming off of the PSSM's audio accessory connector but you are then using the antenna up on your lapel.

I forgot something, with this setup you would have to use the Public safety speaker mics top mounted microphone element for transmitting but you would still have the IMPACTs ear phone for receive, this looks like the only options for this kind of setup.
Mike