voice levels at the repeater input

[mistered4805]

I'm a newby and not certified as a Motorola man but I have extensive electronic background and have a problem at a repeater. We changed out a MSF5000 vhf repeater to a narrowband Quantar repeater. The old MSF was keyed remotely through a 4wire circuit with keying tones emulated at a 4wire channel card. We could access the link at a console 40 miles beyond the range of the repeater over this 4wire line; and we used this without any problems for years.

The new Quantar radio was installed with a consolette; a 2000 series which was set up at the repeater site. Everything works. The installers left the consolette at the repeater, hooked up and working. We decided to relocate the consolette to the other end and operate the same 4wire circuit as before. We did this and have experienced an intermittent problem. The receive at the remote is perfect, but the transmit is intermittent. It only keys about 6 out of ten keys, when it keys, the other end, and the mobiles copies us perfectly. There is over 10 volts p-p voice (keying tones are about a volt higher) hitting the channel out of the consolette. The channel output at the other end ( is at about 5 volts p-p (keying tones are a bit higher). And I might add the levels are almost the same as the original levels at the originate end. I am thinking the installers set this thing up for a local console and not a remote console. HELP!

I need to know what levels the Quantar needs to see at the interface for the voice and key tones.
I need to know what software if needed is necessary for the Quantar, or if it might be a strap that
allows for different interfacing levels, and different impenance matches. I know the channel equipment is working and I know the repeater and consolette are working; I think I have a mismatch in the level hitting the repeater.

My 4wire cards are standard +7dbm receive and -16dbm transmit; I can take some atten out of the receive side if needed.

Thanks for any ideas...Ed

[wavetar]

They may have set the remote for 'local' operation, with the line output set for -10dBm, as opposed to 'remote' operation, which would normally be set for 0dBm. It can also be set up to a maximum of +11dBm in 1dB increments, in case you need to nudge it up (I'm assuming you mean MC2000 as the console). The procedure for doing so is done with the deskset buttons, and is a bit involved. I can email you the needed pages from the manual if you PM me your email address.

Todd

[mistered4805]

Wavetar
Thanks for the input and our consolette designation is actually a MC1000 / L3211. I want to insure the Quantar is set up right. It appears that the level coming out of the channel is at channel spec which is +7dbm receive to the wire line interface board, but it may not be high enough for the Quantar. I don't want to raise the level out of the consolette for fear of overdriving the channel. The channel is on a T1 with other data circuits. I acquired a book today on the Quantar and will probably get this figured out. This is a neat forum; I've learned a lot already. Ed

[mistered4805]

wavetar
Thanks for your response. It turns out that the channel level +7 far exceeds what Motorola expects on the input. We padded it down to -10 and it keys every time. Apparently it was being overdriven. Thanks again. Ed

[Z Barebow]

This was very likely not a Motorola hardware problem.

If using a T1, you use voice cards to convert from analog audio to T1 transmission. Typically the cards will not tolerate levels greater than 0 db. When you hit them with greater levels, they distort the audio and the tone decoding equipment had problems decoding the "molested" keying tones.

You must also keep in mind the relationship between keying tones and audio.

High level Guard tone-HLGT is the highest component and should be set no greater than 0db. If set at 0 db, Low Level Guard Tone will be at -30 db. This is the level to base your level setting procedure.

Do the settings on the remote reflect max keying tone level, or max voice level. (Two different things). Some remotes have independant audio adjustments, others have one control which governs all tx audio, (Keying tones and composite audio).

Brian

[George]

Lesson 1 of Telephony 101

Carrier systems are set up for voice transmission with levels of -16 in for a +7 out.

Carrier means stuff like T1 circuits. The T1 will feed a channel bank and you get your four wire circuit from the channel card or output from the channel bank. This is to be presented as four wires. Okay, four wire may be a pain for multiple remotes, but hey, you can handle this on the remote end and convert it to two wires.

Keep that in mind when setting up a circuit from a remote to a base station.

This starts to get into the pissing contest between the radio user and the telephone company. If your telephone company uses a far end term unit, those circuits can do a loopback to ensure the right levels are present when they test a circuit. If you screw around with the levels, they send someone out to correct the problem you just created.

The way to solve this is IF you are working with carrier systems, you put a pad on your receive side like a Tellabs 4201 or something like that to knock down the level to your base.

On the other side, send a -16 instead of a 0. That will keep from overdriving the carrier channel.

Done! No more arguements with the telephone company.

George.......zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzwake me when I need to go homezzzzzzzzzzzzzzz.