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[Diogo Nunes Pereira]

Hello everybody,

I'll be showering the meager knowledge of RF and frequency coordination I have with a group of technicians here in Spain for a couple of days.

We will be covering the fundamental theory of RF (wave equation, path loss, link budget, unit conversions ...), wireless systems (modulation types, companders, interference, intermodulation, diversity reception, antenna polarization, etc...) and frequency coordination in a class setting with some demos along the way.

Here's where I need some help from this gentle forum guardians: good ideas for demoing this concepts with the scarce RF equipment and analyzers in our hands. I have some stuff lined up, but would love to have some more from the ark of accumulated experience that populates this pages.

The gear at our disposal will be:

4x sennheiser EW100 receivers (with ASA-1 splitter, whips and A2003 passive fins)
2x sennheiser EW500G3 receivers (with whips)
Handheld, bodypack and plug-on transmitters for the above
Long cables, short cables and antenna boosters

4x sennheiser IEM transmitters (with a combiner)
1x sennheiser A5000 helical antenna

1x shure ULX-D receiver (with 2 mics and whips)

1x Altair WBS-200 Intercom (which I've never used before)

RF Explorer (running with windows client software and Nuts about Nets Touchstone software)
SDR-Dongle (running SDR# software)
Shure Wireless Workbench 6 (can't afford IAS for now...)

All ideas are welcome, even the small ones.  Gracias in advance.

Diogo

[John Sulek]

Hello everybody,

I'll be showering the meager knowledge of RF and frequency coordination I have with a group of technicians here in Spain for a couple of days.

We will be covering the fundamental theory of RF (wave equation, path loss, link budget, unit conversions ...), wireless systems (modulation types, companders, interference, intermodulation, diversity reception, antenna polarization, etc...) and frequency coordination in a class setting with some demos along the way.

Here's where I need some help from this gentle forum guardians: good ideas for demoing this concepts with the scarce RF equipment and analyzers in our hands. I have some stuff lined up, but would love to have some more from the ark of accumulated experience that populates this pages.

The gear at our disposal will be:

4x sennheiser EW100 receivers (with ASA-1 splitter, whips and A2003 passive fins)
2x sennheiser EW500G3 receivers (with whips)
Handheld, bodypack and plug-on transmitters for the above
Long cables, short cables and antenna boosters

4x sennheiser IEM transmitters (with a combiner)
1x sennheiser A5000 helical antenna

1x shure ULX-D receiver (with 2 mics and whips)

1x Altair WBS-200 Intercom (which I've never used before)

RF Explorer (running with windows client software and Nuts about Nets Touchstone software)
SDR-Dongle (running SDR# software)
Shure Wireless Workbench 6 (can't afford IAS for now...)

All ideas are welcome, even the small ones.  Gracias in advance.

Diogo

I did a similar thing and found that using the rf scanner to show the difference between an iem transmitter with and without program input helped to illustrate the deviation spec, and why you space out the transmitter frequencies a bit .
Also eye opening to show people what happens when you overload the audio input of the transmitter.

Walking through an onsite coordination with the gear you have is a good way to generate questions and answers.

I was at a Shure demo once where they handed us a bunch of assorted antennae, boosters and cable and challenged us to get the best reception of a mic at the other end of the convention center hallway. That was a good demo of what boosters vs antenna selection could accomplish.

Hope it goes well!

[Diogo Nunes Pereira]

I did a similar thing and found that using the rf scanner to show the difference between an iem transmitter with and without program input helped to illustrate the deviation spec, and why you space out the transmitter frequencies a bit .
Also eye opening to show people what happens when you overload the audio input of the transmitter.

Walking through an onsite coordination with the gear you have is a good way to generate questions and answers.

I was at a Shure demo once where they handed us a bunch of assorted antennae, boosters and cable and challenged us to get the best reception of a mic at the other end of the convention center hallway. That was a good demo of what boosters vs antenna selection could accomplish.

Hope it goes well!

Hey John, thank you for your input. Your suggestions did made the bill...

Among others, we did the following:

- Polarization (Hor. vs Vert.) - Rx antennas @ 90º and changing the beltpack position to show how receiver changes antenna selection
- Deviation (as you proposed) - looking at the analyser with and without signal up to input limiting
- Selectivity - Tuning out a Tx from Rx frequency to find when signal dropped out
- Noise squelch - related to the above; Also tuning on top of high level TV channel and getting the squelch circuit to mute above; also how noise squelch influences system range.
- Tone Key - tuning Shure Tx to Sennheiser Rx receiver with Tone Key activated
- Coverage with different antennas (dipoles, paddles, helical)
- Omni scanning vs. directional scanning to find the nearest TV transmitter.
- Coordination exercises; zone coordination; inclusion lists in WWB
- Analog FM spectrum mask vs. Digital modulation (ULX-D) spectrum mask
- War-gaming
- Walk tests

One curious thing we all found out was that a digital mic can fool the Tone Key circuit of an analog receiver... I tuned 3 different mics to the same Sennheiser ew500 Rx frequency with tone key activated:

 - 1 Senn 500 Tx with tone key on - open gate
 - 1 Senn 500 Tx with tone key off - closed gate
 - 1 Shure ULX-D - open gate (OOOPS - Beware!!!)

It was a cool couple of days... Next week I do it again with another group.

Still eager to ear from more people.

Cheers,

Diogo

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