Any StarPlex gurus out there?

[d119]

I've got some questions about point-to-point microwave links, and I know nothing about these types of things.

I'm curious what it would take to set up a bare-bones StarPlex point-to-point microwave shot on the 900MHz amateur band. Main point of this is to link back remote voting receivers.

What is the minimum antenna configuration, radio configuration, shelf configuration, etc? I'd like to have at least 2 audio paths from the receiver site back to the comparator.

The shot is less that 1/4 mile and both sites can see each other just fine.

Can someone give me the low-down on how these StarPlex systems work?

Much obliged, in advance.

[xmo]

Analog mux [Starplex]

Mostly a lost art. Frequency selective level meters, noise power ratios, 75 ohm this, baseband that. Ahh - the good old days.

Starpoint radios went with the Starplex and Starplus mux and were 1.8 GHz, 2.3 GHz and above.

Your best bet there would be moving a 2.3 GHz system into the 2.4 GHz ham band.

There were two 900 band Motorola products that might work for you, MR92 and MR96. [M= microwave, R=radio, 9=900 band, 2 or 6 analog mux channels]

Either should move down to the ham band just fine.

[d119]

xmo,
Thanks for the info. What kind of antennas would be needed for these MR92 and MR96 radios for a 1/4 mile link? Where can I locate these radios? How difficult is it to interface them?

Thanks much!

[psapengineer]

Here's a side note:

One company still makes this kind of stuff today. Formerly this line was made by Cardion. Today Nutel Wireless makes the product line; analog mux and analog 900 Microwave.

Here's the links:

http://www.nutelwireless.com/Nutel/8000.html

http://www.nutelwireless.com/Nutel/9500.html

[Bob W]

xmo,
Thanks for the info. What kind of antennas would be needed for these MR92 and MR96 radios for a 1/4 mile link? Where can I locate these radios? How difficult is it to interface them?

Thanks much!

I don't know anything about those particular radios, but at a 1/4 mile any antenna ought to be sufficient from a mag mount cellular antenna (just to test) to a Yagi (the likely candidate).

[psapengineer]

Here's a bit on antennas:

Its really bad practice to use an omni directional antenna in a point to point application. Antennas should be highly directional. This does several things for the path. It increases gain in the direction you need the gain, increases margin, increases performance, increases reliability, and increases availability. It also decreases unwanted interference that can harm your receiver thereby improving carrier to interference ratio, protects other's receivers from your transmitter, and allows re-use of the channel pair by other azimuths in the not too far distance. This is all microwave path engineering stuff.

In 960 Licensed microwave you're required to use a really good antenna meeting a beamwidth specification that is relatively narrow. It would be good practice to use the same model antennas in the amateur band; but, they are really expensive. Examples of these are parabolic grids, parabolic reflectors and solid parabolic dishes. The least costly of these would be the parabolic reflector.

Good Luck, Bob

[Bob W]

I guess a more basic question is why the questions about StarPlex? Do you have a pair of shelves, and modems? If you do, the commercial 950 radios may not be the best solution, as they likely will not go down to 902-928 with replacing filters, etc. Licensing it - if you could - in the 950 MAS band isn't an option as you could not then use it to carry amateur traffic. The 2300 radios may not go to the 2.4ghz ham band for the same reason - filters, multipliers, PLLs (if applicable). Assuming you've got the shelves, and the modems, and the modems will run on the lower channels in the baseband, you could use ATV transmitters and receivers in any band that you could get them in. A pair of yagi antennas on each end would eliminate the need for a duplexer. Heck, we're talking about 1300 feet here, so likely, mere milliwatts would get the job done.

If you want to get real creative, you could even modulate lasers with the baseband output of the shelves and extract the carriers for the recieve side with a pin photo detector.

As for my comments about omni antennas, note the word test after mag mount cellular. In his app, the most reasonable antenna would be a yagi. A nine foot grid antenna would be overkill (but I've got an extra one with a bad feedhorn (too much seaweed, and seagull!))

Another possibility at this short range is to find a source of some type of audio encoder that would take audio, digitize it, and make I/P packets out of it. You could then use normal 802.11B/G radios on a channel that corresponds to frequencies in the 2.4ghz amateur band.

[d119]

It just seems a more logical and proper way to use 900MHz to link back the voting receivers. That's why.

I can't see putting a 900MHz MaxTrac in continuous transmit (even at low power levels) to link back the voting receivers. Plus, the microwave would allow me to send other things from the remote sites back to the comparator site.

I can't seem to find ANYTHING on these MR92 or MR96 radios. Can someone give me more information?

Thanks!

[George]

[quote="xmo"]Analog mux [Starplex]

Mostly a lost art. Frequency selective level meters, noise power ratios, 75 ohm this, baseband that. Ahh - the good old days.

Starpoint radios went with the Starplex and Starplus mux and were 1.8 GHz, 2.3 GHz and above.

Your best bet there would be moving a 2.3 GHz system into the 2.4 GHz ham band.

There were two 900 band Motorola products that might work for you, MR92 and MR96. [M= microwave, R=radio, 9=900 band, 2 or 6 analog mux channels]

Either should move down to the ham band just fine.[/quote]


Do you or anyone have any MUX for these radios? I have the radios, need the mux shelves.

[SlimBob]

Does anyone have a hard figure as to how much loss bird sh** contributes?

[tvsjr]

Does anyone have a hard figure as to how much loss bird sh** contributes?

African or European bird sh**?

[N4DES]

Analog mux [Starplex]

Mostly a lost art. Frequency selective level meters, noise power ratios, 75 ohm this, baseband that. Ahh - the good old days.

Oh yeah those were the good ol days to include the time spent at Schaumburg doing microwave concepts I and II, which meant 2 full weeks in IL.
I think it that was the only training at Motorola U that actually had an exam at the end.

[motorola_otaku]

If you just need analog audio, why not go with a couple of DARCOM 9000 radios? One, they're built for 902-928, and two, they're full-duplex. I know they were intended for SCADA applications, but it shouldn't be too hard to pass voice through them. I would use them for simple repeater linking if I could ever find them on the used market.

Only bad thing is they're rockbound, so if you did find a pair and they were set for different frequencies it's off to ICM.. assuming they can even work with the channel elements those things use.

[d119]

If you just need analog audio, why not go with a couple of DARCOM 9000 radios? One, they're built for 902-928, and two, they're full-duplex. I know they were intended for SCADA applications, but it shouldn't be too hard to pass voice through them. I would use them for simple repeater linking if I could ever find them on the used market.

Only bad thing is they're rockbound, so if you did find a pair and they were set for different frequencies it's off to ICM.. assuming they can even work with the channel elements those things use.

Evidently you haven't looked very hard.

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