OpenSpot2 Issues

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KM4RT
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OpenSpot2 Issues

Post by KM4RT »

Good morning!

I have an OpenSpot2, and an enjoying it except for a few issues I keep having dealing with other stations telling me that my audio keeps chopping / dropping out. This seems to happen most often when I am crossing over to the DMR side using my Fusion radios.

I use all C4FM Fusion radios to connect to either the YSF Reflectors or to cross over to DMR. I have an FT2D handheld, an FTM-400XDR in the truck, and an FTM-400XDR at my house and use all these with the OpenSpot2. When I am mobile, I link the OpenSpot2 to my cell phone hotspot.

First, I have come to the conclusion that I need to run all my Fusion radios in the FM Narrow modulation mode and the Half Deviation mode in the OpenSpot2 so that the receive frequency offset can be calculated. I have found that the receive frequency offset is different for each radio and tends to vary when I run AutoCAL (perhaps inherent radio frequency instability due to temperature?).

Question 1 - is it true that I should be using the FM Narrow mode on my radios and Half Deviation mode on the OpenSpot2? Or is it better to not use FM Narrow mode? It appears that the receive offset can only be set if I'm running in narrow mode.

Question 2 - does the receive frequency offset setting affect only receive audio or both receive and transmit audio?

Now, when using my mobile phone to connect the OpenSpot2 to the internet, I believe I understand that the Dejitter setting must be higher than the default 500 ms. I have been using 1000 ms, but perhaps this should be much, much higher?

Question 3 - how do I know how high to set the Dejitter setting?

Question 4 - is there some setting to change to improve the Bit Error Rate?

Thanks in advance.
KM4RT

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HA2NON
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Re: OpenSpot2 Issues

Post by HA2NON »

It's advised to turn off half deviation mode in the transceiver, if there's an option for that (not all Fusion transceivers let you turn off half deviation). In this case, use plain C4FM (not C4FM Half Deviation) modem mode in the OS2. Plain C4FM mode does not need AutoCal.

RX offset only affects OS2 RX.

1000-1500ms is good for cellular network connections. If you see that the dejitter queue often gets emptied while a call is ongoing, then you should increase it's size. You can see the dejitter queue's state on the dejitter queue graph (Status page).

If you can't turn off half deviation mode in your transceiver, then yse C4FM Half Deviation AutoCal to find the RX offset for your transceiver, or manually adjust the RX offset on the Modem page in +-100Hz steps to find the lowest BER.

Also try using different servers.
Norbert "Nonoo" Varga, HA2NON
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Re: OpenSpot2 Issues

Post by LA9ULA »

The term "half deviation" used here causes me some problems. I find no reference to it in the Yaesu manuals.
Could someone please help explain it to me.

I have a Yaesu FT3D and a FTM400XDE, Both have the same choices as follows for digital modes:

1) V/D (voice & data are transmitted simultaneously) also referred to as DN
2) Voice FR Mode (voice full rate mode) also referred to as VW

I understood "DN" to mean Digital narrow" - but perhaps that is wrong?
Both modes use 12,5 kHz, but VW uses all for voice and DN uses simultaneous half of it for voice and half for data.
There are no option to turn off or on what is referred here as "half deviation"
There is, however a possibility to choose wide or narrow "FM bandwidth", but I thought that only affected analog FM?

Referring to the term "half deviation" - what are the two modes 1) and 2) above, half or full or "plain" C4FM?

Regards
Bjørnung

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Re: OpenSpot2 Issues

Post by HA2NON »

Probably the FT3 does not support normal (12.5kHz) deviation. As far as we know the FTM400 does support switching between half (6.25kHz) and normal deviation in the menu. This has nothing to do with the used mode (DN or VW).
Norbert "Nonoo" Varga, HA2NON
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Re: OpenSpot2 Issues

Post by LA9ULA »

Thank you Norbert,

I realise this is not directly related to the OpenSpot, but for user of these radios it might be useful.
After closer study of the user manuals I found settings that does in fact allow AutoCal to recognize a transmission and complete, it did not do that before I changed the settings in any of the two radios I have.

I take that as a sign that I did find the half deviation settings in both radios and that they both have "normal" or full deviation as well. Norbert - correct me if I am wrong.

For the FT3D in the set mode: under TX/RX, 1 Mode, 2 FM Bandwith, select either wide or narrow

For the FTM400 in the set-up menu: TX/RX, MODE, select either FM or Narrow FM

Yeasu seems to refer to this as either "signal format", "switching the modulation mode", or "setting transmission modulation level" in the manuals.

A comment to KA4RT who writes: "First, I have come to the conclusion that I need to run all my Fusion radios in the FM Narrow modulation mode and the Half Deviation mode in the OpenSpot2 so that the receive frequency offset can be calculated."

My understanding is that narrow is NOT the best option if you can choose full FM, but is the only one that AutoCal will work on. Best is to use full FM (full) with "normal deviation mode" in the OS2.

I hope this is correct and that I will not mislead anyone.
Hopefully someone will quickly correct me if necessary.

Bjørnung

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Re: OpenSpot2 Issues

Post by HA2NON »

If half deviation mode is not used on the transceiver, then no AutoCal is required on the openSPOT. That's why the AutoCal is called C4FM Half Deviation AutoCal.
Norbert "Nonoo" Varga, HA2NON
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Re: OpenSpot2 Issues

Post by LA9ULA »

Thanks Norbert

- makes sens of course :D

regards
Bjørnung

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