Some hotspot woes... Bad intelligibility

[EA7KLK]

Also, here are the logs from MMDVM:

On the OpenGD77 / Radio hotspot:

Code: Select all

M: 2024-01-21 20:51:21.687 DMR Slot 2, received network voice header from 9990 to EA7KLK
M: 2024-01-21 20:51:24.526 DMR Slot 2, received network end of voice transmission from 9990 to EA7KLK, 3.0 seconds, 0% packet loss, BER: 1.2%

On the duplex MMDVM hotspot:

Code: Select all

M: 2024-01-21 20:55:12.421 DMR Slot 1, received network voice header from 9990 to EA7KLK - Name:
M: 2024-01-21 20:55:15.878 DMR Slot 1, received network end of voice transmission from 9990 to EA7KLK, 3.7 seconds, 0% packet loss, BER: 0.0% - Name:

Both transmissions are from roughly the same distance. It seems my RT84 has gone deaf? Or have I missed some adjustment in OpenGD77 that could negatively influence the signal strenght?

[F1RMB]

A 3 seconds sample is way too short to get the BER as an accurate value.

Also, it would be better to make a video to demonstrate your problem, using Parrot, and this for many seconds.

[VK3KYY]

Also AFIK the BER shown at the end of the transmisson is Not the average BER of the entire transmission, its the last BER from MMDVMHost

But I agree with Daniel, you need to transmit for longer than a few seconds and BER is not a super good measurement of whether the signal is readable.

BER has to be very high before the signal breaks up.

[EA7KLK]

OK, thanks for all the great help so far...

Here is a video I've made, where you can get an accurate idea of how it sounds:
youtu.be/9hhBGwl7R2E

For good measure, I am attaching my MMDVM config. Maybe I have overseen something there:

Code: Select all

[General]
Callsign=EA7KLK
Id=2140410
Timeout=240
Duplex=0
RFModeHang=300
NetModeHang=300
Display=None
Daemon=1

[Info]
RXFrequency=430400000
TXFrequency=430400000
Power=3
Latitude=50.00
Longitude=-3.00
Height=0
Location="Town, L0C4T0R"
Description="Country"
URL=https://www.qrz.com/db/EA7KLK

[Log]
DisplayLevel=0
FileLevel=2
FilePath=/var/log/pi-star
FileRoot=MMDVM

[CW Id]
Enable=0
Time=1

[DMR Id Lookup]
File=/usr/local/etc/DMRIds.dat
Time=24

[NXDN Id Lookup]
File=/usr/local/etc/NXDN.csv
Time=24

[Modem]
Port=/dev/ttyACM0
TXInvert=1
RXInvert=1
PTTInvert=0
TXDelay=100
RXOffset=0
TXOffset=0
DMRDelay=0
RXLevel=100
TXLevel=100
RXDCOffset=0
TXDCOffset=0
RFLevel=50
CWIdTXLevel=50
D-StarTXLevel=50
DMRTXLevel=50
YSFTXLevel=50
P25TXLevel=50
NXDNTXLevel=50
POCSAGTXLevel=50
RSSIMappingFile=/usr/local/etc/RSSI.dat
Trace=0
Debug=0
M17TXLevel=50
FMTXLevel=50
AX25TXLevel=50
UseCOSAsLockout=0
UARTSpeed=115200
Protocol=uart
UARTPort=/dev/ttyACM0

[Transparent Data]
Enable=1
RemoteAddress=127.0.0.1
RemotePort=40094
LocalPort=40095

[UMP]
Enable=0
Port=/dev/ttyACM1

[D-Star]
Enable=0
Module=B
SelfOnly=1
AckReply=1
AckTime=750
ErrorReply=1
RemoteGateway=0
ModeHang=20
AckMessage=0

[DMR]
Enable=1
Beacons=0
BeaconInterval=60
BeaconDuration=3
ColorCode=1
SelfOnly=1
EmbeddedLCOnly=0
DumpTAData=1
CallHang=3
TXHang=4
ModeHang=20
OVCM=0
Id=214041001

[System Fusion]
Enable=0
LowDeviation=0
SelfOnly=1
TXHang=4
RemoteGateway=0
ModeHang=20

[P25]
Enable=0
NAC=293
SelfOnly=1
OverrideUIDCheck=0
RemoteGateway=0
ModeHang=20
TXHang=5

[NXDN]
Enable=0
RAN=1
RemoteGateway=0
TXHang=5
SelfOnly=1
ModeHang=20

[POCSAG]
Enable=0
Frequency=439987500

[D-Star Network]
Enable=0
GatewayAddress=127.0.0.1
GatewayPort=20010
LocalPort=20011
Debug=0
ModeHang=20

[DMR Network]
Enable=1
Type=Direct
Address=2141.master.brandmeister.network
Port=62031
Jitter=360
Password=No frigging way ;) 
Slot1=0
Slot2=1
Debug=0
ModeHang=20
RemoteAddress=2141.master.brandmeister.network
RemotePort=62031

[System Fusion Network]
Enable=0
LocalAddress=127.0.0.1
LocalPort=3200
GatewayAddress=127.0.0.1
GatewayPort=4200
Debug=0
ModeHang=20

[P25 Network]
Enable=0
GatewayAddress=127.0.0.1
GatewayPort=42020
LocalPort=32010
Debug=0
ModeHang=20

[NXDN Network]
Enable=0
LocalAddress=127.0.0.1
LocalPort=14021
GatewayAddress=127.0.0.1
GatewayPort=14020
Debug=0
Protocol=Icom
ModeHang=20

[POCSAG Network]
Enable=0
LocalAddress=127.0.0.1
LocalPort=3800
GatewayAddress=127.0.0.1
GatewayPort=4800
ModeHang=5
Debug=0

[TFT Serial]
Port=/dev/ttyAMA0
Brightness=50

[HD44780]
Rows=2
Columns=16
Pins=11,10,0,1,2,3
I2CAddress=0x20
PWM=0
PWMPin=21
PWMBright=100
PWMDim=16
DisplayClock=1
UTC=0

[Nextion]
Port=/dev/ttyAMA0
Brightness=50
DisplayClock=1
UTC=0
ScreenLayout=0
IdleBrightness=20

[OLED]
Type=3
Brightness=0
Invert=0
Scroll=0
Rotate=0
Cast=0
LogoScreensaver=0

[LCDproc]
Address=localhost
Port=13666
DimOnIdle=0
DisplayClock=1
UTC=0

[M17]
Enable=0
CAN=0
SelfOnly=1
TXHang=5
ModeHang=20

[AX 25]
Enable=0
TXDelay=300
RXTwist=6
SlotTime=30
PPersist=128
Trace=0

[M17 Network]
Enable=0
LocalAddress=127.0.0.1
LocalPort=17011
GatewayAddress=127.0.0.1
GatewayPort=17010
ModeHang=20
Debug=0

[AX 25 Network]
Enable=0
Port=/dev/ttyp7
Speed=9600
Debug=0

[Lock File]
Enable=0
File=/tmp/MMDVMHost.lock

[Mobile GPS]
Enable=0
Address=127.0.0.1
Port=7834

[Remote Control]
Enable=0
Port=7642
Address=127.0.0.1

[FM]
Enable=0
Callsign=M1ABC
CallsignSpeed=20
CallsignFrequency=1000
CallsignTime=10
CallsignHoldoff=0
CallsignHighLevel=50
CallsignLowLevel=20
CallsignAtStart=1
CallsignAtEnd=1
CallsignAtLatch=0
RFAck=K
ExtAck=N
AckSpeed=20
AckFrequency=1750
AckMinTime=4
AckDelay=1000
AckLevel=50
Timeout=180
TimeoutLevel=80
CTCSSFrequency=94.8
CTCSSThreshold=30
CTCSSHighThreshold=30
CTCSSLowThreshold=20
CTCSSLevel=20
KerchunkTime=0
HangTime=7
AccessMode=1
COSInvert=0
RFAudioBoost=1
MaxDevLevel=90
ExtAudioBoost=1

[AX.25]
Enable=0
TXDelay=300
RXTwist=6
SlotTime=30
PPersist=128
Trace=0

[AX.25 Network]
Enable=0
Port=/dev/ttyp7
Speed=9600
Debug=0

[EA7KLK]

OK,

it seems the problem is solved. I changed the hotspot frequency just before the problems started appearing, namely to 430.400 MHz as one of the recomended frequencies for hotspots in Spain as per this page: https://ea1uro.com/radio/dmrsimplex/

Although I checked, with both analog and digital radios if that frequency was clear for quite a while, well, at least for some minutes, and I also did a sweep scan with the OpenGD77 radio in this band for a while, it seems it wasn't clear enough.

I wonder if the military comms installation nearby (huge antennas, microwave dishes, well within my line of sight has anything to do with it. Harmonics strong enough to bother me around 2Km away? Sounds plausible.

Fact is: I moved to 439.825 as the frequency for the OpenGD77 hotspot, and all is fine now.

Note to self: Do changes one at a time. If one tends to forget stuff, make a log of the changes. Saves lots of pain and time.

Sorry for bothering you all with this issue, and thanks for all the assistance.

[VK3KYY]

I have a lot of local QRM on 2m but 70cm is better

In your case, why not use 2m? The range will be better than on 70cm

[EA7KLK]

I have a lot of local QRM on 2m but 70cm is better

In your case, why not use 2m? The range will be better than on 70cm

No space for a half decent 2m antenna. Got myself a homebrew 70cm GP from 10€ of parts, though:

2024-01-23 08.55.07.jpg (104.54 KiB) Viewed 979 times

[VK3KYY]

You could easily use a single or dual band J-Pole or a flower-pot antenna.

You can make both of these from things you can buy at a hardware store and are very cheap to make and perform well.

Also, get some more clamps and clamp the antenna to the balcony rail.
Don't use those spring loaded clamps, get the ones which use the same mechanism as silicon sealant dispensers, as they don't have a screw thread and will be more water resistant

Edit.

Actually get a longer support tube from a hardware store and also buy some plastic cable ties, you can then use the cable ties to hold the support tube to the corner of the balcony railing.

[EA7KLK]

Actually get a longer support tube from a hardware store and also buy some plastic cable ties, you can then use the cable ties to hold the support tube to the corner of the balcony railing.

I'm cursed with neighbours and an HOA that are particularly sensitive to "the aesthetics and uniform appearance of the building" so right now I'm cursed with being as stealty as possible. However, the flower pot antenna idea sounds quite exciting, I'll investigate that one.

[SA0BUX]

Actually get a longer support tube from a hardware store and also buy some plastic cable ties, you can then use the cable ties to hold the support tube to the corner of the balcony railing.

I'm cursed with neighbours and an HOA that are particularly sensitive to "the aesthetics and uniform appearance of the building" so right now I'm cursed with being as stealty as possible. However, the flower pot antenna idea sounds quite exciting, I'll investigate that one.

Yeah, put some larger pot with some large and high plant (maybe a plastic one) near the outside of the balcony and put some j-pole or slim-jim near the stem.
Or a hidden ground plane.

I have a diamond 770 on my balcony that works fine.
That antenna and some similar ones doesn't need any ground plane which is good.