Openspot 1 basics

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G0HXT
Posts: 3
Joined: Sun Aug 02, 2020 8:33 am

Openspot 1 basics

Post by G0HXT »

Hi everyone

Probably an odd request but can anyone point me to some more basic information about the Openspot 1. The manual explains how to configure however, there is nothing that explains what the various terms used mean. When you're completely new to this it is very confusing.

Tyrbiter
Posts: 563
Joined: Thu Dec 22, 2016 11:25 pm

Re: Openspot 1 basics

Post by Tyrbiter »

If you list the terms you are finding confusing then we can probably begin to help here and then possibly find an external resource to give you more information.
Brian G8SEZ

G0HXT
Posts: 3
Joined: Sun Aug 02, 2020 8:33 am

Re: Openspot 1 basics

Post by G0HXT »

Thanks Brian

I guess I'm missing some basic knowledge for example (currently I'm focusing on DMR to keep things simple).

What is the difference between the 3 connectors under DMR. What is Quick Call for and which servers should I connect to when in the UK. Most of the options on the connector page are a mystery to be honest.

DMR SMS - when is this used and what do the options on that page do.

Modem page, I think are relating to the device you use to connect to the hotspot so I would say I'm OK with these and would go with defaults unless there was more information. Most of the options on settings are a mystery but again, if the defaults are OK I would leave until knowledge builds up a bit.

One final questions, why does the system require you to put the modem frequency in both the Connectors page and the Modem page. Are they the same thing or is there a difference?

Thanks for coming back to me.

Tyrbiter
Posts: 563
Joined: Thu Dec 22, 2016 11:25 pm

Re: Openspot 1 basics

Post by Tyrbiter »

G0HXT wrote:
Sun Aug 02, 2020 4:34 pm
Thanks Brian

I guess I'm missing some basic knowledge for example (currently I'm focusing on DMR to keep things simple).

What is the difference between the 3 connectors under DMR. What is Quick Call for and which servers should I connect to when in the UK. Most of the options on the connector page are a mystery to be honest.
The 3 options for the connector relate to the protocol used to talk to the server, they are basically:

Homebrew/MMDVM - these were slightly different but over time are becoming more alike. Initially Homebrew only allowed the use of reflectors (essentially like Talkgroups but only one at a time and by convention remapped to TG9 whereas MMDVM (Multimode Digital Voice Modem) allows either Talkgroups or reflectors to be used. Think of it more like the Talkgroup choice being made at the hotspot rather than at the server.

DMRplus dongle - this is falling out of use now, if memory serves it was used by the original DV4mini dongle but those are now able to use newer software that makes them more like the Homebrew/MMDVM and the result is that servers are dropping support for this protocol.

TS repeat connector - from the manual

You can use this connector to repeat calls received from one timeslot to the other one. This is only useful when the modem is in the experimental DMR/BS mode. This connector has no settings.

Modem modes supported in this connector: DMR

Realistically this is not useful, I think people discovered that the openSPOT would need 2 radio chips and 2 antenna ports to make use of the DMR/BS modem mode.

Quick call - does what it says, mainly there to allow older radios that did everything via the codeplug and had often only 16 channels per zone to avoid lots of finger poking in the menus to select different contacts for changing talkgroups. Essentially you can select a reflector with a private call to the reflector number (between 4000 and 5000, but note that the Brandmeister network will remove reflector support at the end of 2020) whereas a group call to a TG number will make the openSPOT direct everything to that Talkgroup even if you subsequently transmit on TG9.

Servers - you have a free choice of servers pretty much anywhere you like but some servers are better suited to the UK than others. I would start with the Brandmeister UK server and also with Phoenix-F IPSC2+ as it covers the other "half" of UK usage. Note that there are now loads of bridges and gateways and multi-protocol servers around where people with just about any digital radio can all talk amongst themselves.
DMR SMS - when is this used and what do the options on that page do.
You can send short messages to specific IDs (which map to a callsign), so providing that someone with that ID is listening on the network it ought to reach them. I don't use it myself, but there is a section in the manual so I'd suggest reading that once you are clearer on the rest of the things I'm trying to describe :)
Modem page, I think are relating to the device you use to connect to the hotspot so I would say I'm OK with these and would go with defaults unless there was more information. Most of the options on settings are a mystery but again, if the defaults are OK I would leave until knowledge builds up a bit.
Yes, this is pretty much it. Probably worth saying that frequency offsets are quite important with C4FM modulation, so you may need to offset the frequency of your radio and/or hotspot a little, usually less than 750Hz as a maximum. It depends a lot on your radio and the openSPOT RF chip. DMR is the most critical for this as the 50% duty cycle transmit burst means there is ~30ms of silence in each frame for the DC parameters in the demodulators to drift off. There is an autocal, it may work for you, but then again it may not. If your BER is above 1% then it probably means you need to investigate why.
One final questions, why does the system require you to put the modem frequency in both the Connectors page and the Modem page. Are they the same thing or is there a difference?
I think they are the same, the Modem settings are there so that you can get setup initially without having to pick a server and all that. I would hope you only need to do this once, and perhaps a second time for modem calibration.

Hope that's useful, feel free to ask more if you need to.
Brian G8SEZ

G0HXT
Posts: 3
Joined: Sun Aug 02, 2020 8:33 am

Re: Openspot 1 basics

Post by G0HXT »

Thanks Brian, this has been really useful and for some reason, I couldn't find this anywhere.

Will have a play and come back if I have more questions :-).

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