chris451rr
Member
When the TRX-1 is operated in fringe areas, I find it will miss a lot of calls, side by side for example to a bc296xt, where it is a mix of UHF 800 VHF with various squelch modes and trunk modes.
In summary the scan speed or dwell time is too fast for weak signals.
This has been verified by using a signal generator and various scan modes.
I warmed up the signal generator to verify the numbers.
TRX 1 running on battery (no ac adapter noise) coax directly to antenna and signal generator.
Program a test frequency and navigate to that channel and adjust the signal generator to determine squelch open point.
Squelch opens at -115dbm on a fixed test frequency 155.160mhz.
Scan only a few channels 155.15626 and 155.160 and one trunked group.
Will stop near -115 dbm.
Scan a huge scan list (numerous bands and systems and CTCSS but including 155.160 carrier squelch.
Misses this channel until power is turned up to -105 to -100.
Clearly when the scanner is changing bands segments and modes it is not keeping up at 70chans/sec.
For whistler: Set up a signal generator on a fixed carrier access frequency.
Set up a scan list of 2 channels, verify it will stop at -115.
NOw set up a scan set of lots of channels bands and modes.
If it is locked down to just a few channels or one system and wildcard, it will catch all the calls.
Also it does well in strong signal areas.
In the specifications it states 70 channels per second scan rate.
That is quite fast for weaker signals and there is no adjustment for this.
So for a given channel DMR
Fixed radio gets 100%
BC296xt will detect all such signals but there is a delay depending on how many channels
trx-1 will miss quite a few calls.
Trx improves quite a bit if locked down to the trunked system and squelch is backed off.
Open squelch helps a lot.
TRX has no decode issues I've seen with DMR here and gets some DMR formats that a fixed channel (baofeng dm5r plus) is not decoding. (I don't have a TYT).
But will miss calls unless locked down to a single channel
will not decode.(two codecs? Some older Motorola DMR codecs are not in the baofeng)
Squelch Signalbar and Trunk do a lot of flashing on/off.
Open squelch and lockout all carrier squelch channels improves hits.
The time constant in the squelch seems too long compared to the scan speed.
When switching to a trunked talk channel that is weak or marginal or simulcast, it will fail to detect it and move on, but is improved when the squelch control is open.
Then the scanner will stop on a carrier access channel and squelch has to be turned back up.
Workarounds:
Reduce channels scanned to a few.
Place high priority channels in several scan sets
Scan a trunked system with wildcard and lock it down to a few high priority channels.
If a call is heard use the left arrow then lock down on the channel(usually the last one heard)
Other issues:
When turning on it is in menu mode and does not start scanning after it boots up.
Battery charging is hard to predict. There is no spec on charging current nor a flow chart for how the timed battery charging works.
Sometimes it will crash when power drops. Very rarely it requires a pull the battery out reset. There does not seem to be a keyboard combo that will reset it.
If it is running it takes a long time to charge - battery seems to give full run time after a day.
Run time on the current set of batteries (NIMH 2.5ah) about 5 or 6 hours.
Could be much less depending on use.
Things I will eventually measure or do if nobody else has:
Charge current when on/off.
Measure current at batteries.
Source 5v current drawn during charge/run/not charging and running/off.
Look for the local oscillator on a spectrum analyzer
Test band sensitivity for a series of frequencies
Try some remote control commands.
In summary the scan speed or dwell time is too fast for weak signals.
This has been verified by using a signal generator and various scan modes.
I warmed up the signal generator to verify the numbers.
TRX 1 running on battery (no ac adapter noise) coax directly to antenna and signal generator.
Program a test frequency and navigate to that channel and adjust the signal generator to determine squelch open point.
Squelch opens at -115dbm on a fixed test frequency 155.160mhz.
Scan only a few channels 155.15626 and 155.160 and one trunked group.
Will stop near -115 dbm.
Scan a huge scan list (numerous bands and systems and CTCSS but including 155.160 carrier squelch.
Misses this channel until power is turned up to -105 to -100.
Clearly when the scanner is changing bands segments and modes it is not keeping up at 70chans/sec.
For whistler: Set up a signal generator on a fixed carrier access frequency.
Set up a scan list of 2 channels, verify it will stop at -115.
NOw set up a scan set of lots of channels bands and modes.
If it is locked down to just a few channels or one system and wildcard, it will catch all the calls.
Also it does well in strong signal areas.
In the specifications it states 70 channels per second scan rate.
That is quite fast for weaker signals and there is no adjustment for this.
So for a given channel DMR
Fixed radio gets 100%
BC296xt will detect all such signals but there is a delay depending on how many channels
trx-1 will miss quite a few calls.
Trx improves quite a bit if locked down to the trunked system and squelch is backed off.
Open squelch helps a lot.
TRX has no decode issues I've seen with DMR here and gets some DMR formats that a fixed channel (baofeng dm5r plus) is not decoding. (I don't have a TYT).
But will miss calls unless locked down to a single channel
will not decode.(two codecs? Some older Motorola DMR codecs are not in the baofeng)
Squelch Signalbar and Trunk do a lot of flashing on/off.
Open squelch and lockout all carrier squelch channels improves hits.
The time constant in the squelch seems too long compared to the scan speed.
When switching to a trunked talk channel that is weak or marginal or simulcast, it will fail to detect it and move on, but is improved when the squelch control is open.
Then the scanner will stop on a carrier access channel and squelch has to be turned back up.
Workarounds:
Reduce channels scanned to a few.
Place high priority channels in several scan sets
Scan a trunked system with wildcard and lock it down to a few high priority channels.
If a call is heard use the left arrow then lock down on the channel(usually the last one heard)
Other issues:
When turning on it is in menu mode and does not start scanning after it boots up.
Battery charging is hard to predict. There is no spec on charging current nor a flow chart for how the timed battery charging works.
Sometimes it will crash when power drops. Very rarely it requires a pull the battery out reset. There does not seem to be a keyboard combo that will reset it.
If it is running it takes a long time to charge - battery seems to give full run time after a day.
Run time on the current set of batteries (NIMH 2.5ah) about 5 or 6 hours.
Could be much less depending on use.
Things I will eventually measure or do if nobody else has:
Charge current when on/off.
Measure current at batteries.
Source 5v current drawn during charge/run/not charging and running/off.
Look for the local oscillator on a spectrum analyzer
Test band sensitivity for a series of frequencies
Try some remote control commands.