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Author Topic: Remote Control Operation (from the car and other places)  (Read 2042 times)
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steve_qix
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« on: August 15, 2017, 01:43:07 PM »

I remotely control my station in Townsend from my car (and from other places) on a pretty much daily basis, and many people have asked me to document what is set up, and how it works.

The operation works quite well, and I have found the whole system to be reliable and very practical.  I use a fairly simple setup - currently do not change bands remotely, but do change frequency.

So, here is an overall description, with some detail, on one way to operate your station remotely.

Equipment Needed

First and foremost you will need a receiver and VFO (preferably the same unit) that can be controlled remotely.  Many commercial transceivers qualify in this respect.
In my operation, I use a Flex 5000 operating at 1 watt (used as a VFO).

The transmitter (in my case, a class E rig) should be able to operate properly over the frequency range you expect to cover while running remote.  Most transmitters cannot be tuned remotely.  Some antenna tuners are "automatic".  In my setup, I use a coax fed dipole, and tune the transmitter for 3880.  I can move +/- 15kHz or so with no adverse effects.

The Internet connection to the shack needs to be fast enough and RELIABLE enough for the job.  Typically, 512kbps in both directions (up and down) should be sufficient.  The Internet connection at the control end (where you are) also has to be equally fast and reliable.  More on this later.

At least one computer is required in the shack, and of course at the control point.  If you are using an SDR, I recommend a separate computer in the shack, used only for the remote operation, but this is not absolutely required, particularly if the computer running the SDR software is good and fast.  I use 2 shack computers in my particular setup.  All computers must have remote desktop sharing servers running.  I use TightVNC which is very good.  This is absolutely required so you can make frequency adjustments, restart or adjust audio interfaces, and generally configure what is happening.  You have to assume that you may lose power while you are out and about, or that something could go wrong that will require you to be able to connect to the shack computer for whatever reason.

IP enabled switches

These devices let you turn on and off various pieces of equipment remotely.  This is very handy.  These devices are typically available on Ebay for very short money.  Well worth having.


Use port redirection (configured in your Internet router) to allow incoming network connections to be routed through your NAT and/or firewall, and on to the destination computer (typically the computer(s) in your shack).

Control channel

Remote operation, unless you are using some sort of integrated application, typically will involve a control channel and a bidirectional audio channel (or possibly separate audio channels, one in each direction).

The control channel facilitates remote transmit/receive.  If you are operating from a car, you *MUST* use a push-to-talk type of setup.  Anything else, such as having to look at and/or handle a computer will be hazardous to piloting the vehicle. 
In my setup, I use an old Radio Shack CB microphone with a condenser element.  The T/R line interfaces to a USB COM port on the computer.  The remote control software (more on this later) transmits the control signals over a network connection back to the shack computer, which has a sensitive relay connected to the COM port, which activates the in-shack T/R system.

Audio Channel

The audio channel is bidirectional.  The microphone in the car contains a small home brew preamp for the condenser mic element, which then interfaces to the sound card within the car computer (a small laptop).  In the shack, the audio coming from the remote control point is fed into the shack audio system. I strongly recommend using your in shack audio chain to process and control the audio coming from the remote end.

Receive audio is fed to the shack computer running the remote control software (more on this later) sound card input, which is then sent over the network to the computer at the control point.  The audio output from the control point computer is then sent to an earbud or can be fed through the car radio.

Software

I use a free application called RemAud (remote audio).  It has its quirks, but in general works well.  The software includes a bidirectional audio channel, a control channel and a timer to time out the transmitter after a preset period of time.

For monitoring, I run the Radio Engineering Associates modulation monitor on the car computer. The monitor software in the car connects back to the monitor running in the shack.  The mod monitor has a feature where the monitor will emit a Beep when there is a carrier loss.  This is a nice feature because you know when you drop the carrier (go to receive) that it actually happened, and you also know if you have an unscheduled carrier loss due to some other cause.  When you are not driving, you can also look at the monitor and check your modulation.

For my setup, I do not keep a remote desktop session active.  This consumes a lot of bandwidth and requires a very healthy network connection.  I only bring up the desktop sharing application when I need to move frequency.

How good does the network need to be?

When driving around in the car and running remote, the 4G network connection has to be fairly good and reasonably consistent in order to minimize packet loss.  I live in a somewhat rural area, and 4G coverage is not perfect.  One thing that helped considerably was the addition of a cell system "repeater".  This device consist of an amplifier and preamp, an outside antenna and an inside the car antenna.  They are not cheap (around $500), but they make a _HUGE_ difference in providing a much more consistent 4G experience.


That is more or less how this is set up.

Hopefully this is helpful.  I have been asked many, many times about the remote setup I'm using.

It is a nice way to go mobile for sure.

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VE3ELQ
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« Reply #1 on: August 15, 2017, 03:16:15 PM »

Very nice set-up Steve well done.  Having worked you a number of times when you were mobile I can attest to the excellent audio quality and big signal because it comes from your base station.  Save for the occasional dead spot drop out I could not tell you were mobile. A great way to go.

73s  Nigel
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« Reply #2 on: August 17, 2017, 09:20:00 PM »

Wow, that's a lot of stuff!  My concern would be if I lost connectivity and was key-down when that happened.  You'd be sending out a carrier until you could reconnect and un-key.  It sounds like you have all that under control though.

In my case, I would need additional bandwidth to stream live video from the shack.  If/when fire shoots out of the transmitter, I can then flip an IP switch which will key the fire extinguisher mounted at the ready above the MOSFET assembly.  It could also serve as an emergency un-key switch. 

Seriously though, my class E station is analog/mechanical in design.  It's about as simple and basic as you can get for building a transmitter like this.  The tradeoff is difficulty with automation and control and safeguards.  I've heard of some guys operating huge tube transmitters remotely (different states even).  That's ballsy!  I'd be too scared to leave my DX-60 on just to go get the mail. 

Jon
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steve_qix
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« Reply #3 on: August 17, 2017, 10:08:40 PM »

There is no doubt about it, you have to have safeguards in place - overload shutdowns, timers, SWR shutdowns - things like that.

Otherwise remote operation should definitely not be attempted  Cool
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