Batboard

We've been testing MotoTrbo for several months now. We are seeing much better repeater coverage than our analog system using mobiles and portables. Our analog system is still wideband. Analog seems to have better coverage than Trbo when using simplex car to car. The MotoTrbo only seems to have about half the range as the analog. I was wondering if this seemed correct or should Trbo be doing just as well as analog in simplex operation?

That doesn't seem right. We have experienced that MotoTRBO far outperforms analog. We have done a good amount of real world testing in our area and find that the TRBO just gets through cleanly.

MOTOTRBO should be providing better coverage than analog in any situation, simplex or repeater operation. In tests in our area, MOTOTRBO clearly outperformed wide-band analog FM in simplex tests.

What version of firmware in the radios and repeaters? That can have a bearing on how the equipment performs. Ideally, they should have the very latest firmware, version R01.08.00. That version has some enhancements that will definitely improve performance.

John Rayfield, Jr. CETma
http://www.rayfield.net

We're using XPR4550s and XPR6550s for testing. Firmware is 1.08. Repeater coverage with Trbo is definitely better than analog. We can talk on Trbo in places that analog is unusable. Simplex operation however has been disappointing. I've programmed 2 channels in the radios using our car-to-car VHF frequency; one digital the other analog. Under testing, when the digital is out of range the user can switch to the analog channel and many times be able to talk. Could I have stuffed the programming somehow? Any walk-throughs on programming a simplex digital channel?

On repeater I understand that it is TDMA format but on simplex what form of digital does it use?
Sorry for the newbie question but I am trying to learn and read up on this stuff in case the new Yaesu Amateur Handheld turns out to be this format?

n9upc wrote:On repeater I understand that it is TDMA format but on simplex what form of digital does it use?

Same. TDMA. On the repeater you can have 2 simultaneous voice/data transmissions. One on time slot A and one on time slot B.

In simplex, it only uses one time slot, so only a single voice or data transmission at a time.

RFguy wrote:In simplex, it only uses one time slot, so only a single voice or data transmission at a time.

So the transmitter pulses on/off, then? Interesting. That would explain why Close Call scanners won't lock on it.

motorola_otaku wrote:

RFguy wrote:In simplex, it only uses one time slot, so only a single voice or data transmission at a time.

So the transmitter pulses on/off, then? Interesting. That would explain why Close Call scanners won't lock on it.

Correct, and the field radios do that regardless of whether it's simplex or repeater...they can only use one slot at any one time. Makes for approx 1/2 power readings on a standard analog wattmeter, so beware of that.

The repeater on the other hand lights up both slots regardless of whether one or both are used, so wattmeter readings for the repeaters are normal.

Make sure that your MOTOTRBO radios all have the latest version firmware.

John Rayfield, Jr. CETma
Rayfield Communications

TreyH wrote:We've been testing MotoTrbo for several months now. We are seeing much better repeater coverage than our analog system using mobiles and portables. Our analog system is still wideband. Analog seems to have better coverage than Trbo when using simplex car to car. The MotoTrbo only seems to have about half the range as the analog. I was wondering if this seemed correct or should Trbo be doing just as well as analog in simplex operation?

Okay, this is going to sound very elementary, but I don't care and I am going to ask it anyway. If you have a MOTO TRBO repeater, which allows two time slots to be used, but then you switch to simplex which takes up BOTH time slots, I assume that means there is NO way to go on simplex AND still monitor the repeater at the same time? To make an analogy, back in the day on old fashioned analog narrow band FM we used a repeater on 155.595. When we went to talk-around, which was simply simplex on 155.595, we still heard the repeater, but I ASSUME that with MOTO TRBO there is NO way to do that, or am I completely misunderstanding this.

good question - i just tested and yes it works. put 1 trbo HT in talk around the other on normal. the talkaround HT still hears the repeater transmissions. transmitting simplex on the HT does take both timeslots, but it transmits the same timeslots / group call that you would expect coming from the repeater.

Thank you for the reply. I wasn't at work when I psoted this, so I wasm't able to try it.

gopher wrote:good question - i just tested and yes it works. put 1 trbo HT in talk around the other on normal. the talkaround HT still hears the repeater transmissions. transmitting simplex on the HT does take both timeslots, but it transmits the same timeslots / group call that you would expect coming from the repeater.

Not quite correct. The field radios do not 'take both time slots' in simplex or repeater mode...they can simply only use 1 of them at a time. The transmitter pulses on/off as it does not transmit on the 'empty' time slot. This is why Motorola states you get a 40% increase in battery life for portables compared to analog mode...they only transmit half the time in digital mode.

Thank you for the update. Is it still correct that there can only be one simplex conversation or can there be two simultaneous simplex conversations?

Only one. There is nothing to synchronize two.

In Simplex digital, you can think of it in the same way that you think of the RF occupying the assigned frequency in analog mode. It will come down to RF contention and interference. If you had 2 separate digital conversations on the same simplex channel, the amount of collision and the resulting degradation would depend on proximity and RF levels between the radios.

i stand corrected - https://digitalham.info/DMR/CONVVSSIMP.JPG definitely pulsing on and off

wavetar wrote:

gopher wrote:good question - i just tested and yes it works. put 1 trbo HT in talk around the other on normal. the talkaround HT still hears the repeater transmissions. transmitting simplex on the HT does take both timeslots, but it transmits the same timeslots / group call that you would expect coming from the repeater.

Not quite correct. The field radios do not 'take both time slots' in simplex or repeater mode...they can simply only use 1 of them at a time. The transmitter pulses on/off as it does not transmit on the 'empty' time slot. This is why Motorola states you get a 40% increase in battery life for portables compared to analog mode...they only transmit half the time in digital mode.