Radio & Comms Interaction

[dbuckley]

Reponding to an oldish post, but.....

 

So portables had to carry 2 radios ... Because they could hear themselves coming back, it felt just like using the beltpacks and they tried to both speak together. I resolved this by adding a small mixer and second receiver on a second channel so both portables could speak.

This is the classic full duplex RF arrangement, and you can buy such systems off the shelf, there's one (or, perhaps, used to be, all I can find today is 2.4GHz product) that has four transmitters and the receiver packaged in a 1u rack box.

 

So portables had to carry 2 radios rather like the old police system.

The first popular police radio system I can remember used the Pye Pocketfone PF1 [link], which had a pysically separate receiver and transmitter, which would exactly suit this purpose, but everything made in the last several decades, icnluding the PF1's sucessor, has tx and rx in one box. But you can get radios that do the transmit and receive functions separately in the one radio body, so a one-box solution to the handheld, such devices are often specified as supporting cross-band repeat operation, and/or full duplex, and this inclues a lot of the cheap Chinese made-product.

 

http://www.pyetelecomhistory.org/prodhist/portables/pf1/2007-08-31-44-crop-1024p.jpg

 

Pic from above link. Note the radio on the right is the transmitter, which has an antenna, which was extended when one wanted to talk, and the receiver on the left has no antenna. It was typically popped into a shirt pocket; the speaker grill is visible on the top surface. It could be used with an earphone arrangement.

[Paul TC]

 

and the receiver on the left has no antenna. It was typically popped into a shirt pocket; the speaker grill is visible on the top surface. It could be used with an earphone arrangement.

 

Just on topic.

 

The receiver did(does) have an antenna, it was a small perforated plate that doubled as the speaker grill under the slotted area.

 

Some radio amateurs when they got hold of them, used to replace this arrangement with a small helical antenna.

 

As for the transmitter, pressing the PTT button ejected/extended the antenna which could be a hazard, the little white cap on the end of the antenna never survived contact with the average Police user.

 

Problem of the user hearing themselves was not usually an issue as the units normally worked to a base station connected to a control room, who had control of "talk-through", i.e. rebroadcast of incoming audio to outgoing audio, which was only enabled on request, or link failure.

[dbuckley]

As for the transmitter, pressing the PTT button ejected/extended the antenna

I'd totally forgotten that's how the antenna was extended!

 

The receiver did(does) have an antenna

That's what happens when one forgets to note external antenna :)

[sunray]

I have voted 'Yes' in the poll on the basis that under some circumstances it can be very handy, verging on needed. To date I have only used a 'Tecpro' type comms system a handful of times (~30) and of those one would have been extremely difficult to use without a radio element. Another 2 occasions radios were used for absolutely no good reason and only added the unnecessary complication of battery charging, the owner of the 2nd system is prone to use technology whenever possible regardless of whether it's useful or not. for example his desk lamps sit on DMX dimmers on the stage lighting desk.

[AnthonyHunt]

Hi All,

 

Currently, I'm using both radio and Tecpro. I'm a sound engineer and we have Tecpro as our master ring (ASM, MD, Lights and Sound). We are currently experimenting with radio's standalone on several channels for various reasons:

-ASM to crew (for unsighted scene changes/cues)

-Sound to stage tech (Pack faults etc)

-ASM to Chaperones

-FOH Manager to stewards

 

Currently I wear an ASL headset and the PMR earpiece (Baofeng BF-888s Plus) over the same ear (the ASL only on half an ear so I can still hear stage perfectly). It can be a little uncomfortable at times.

 

We have a AD913 and I'm currently making the correct loom for it as the PMR JNR cable I bought to use with Cobra PMR's was noisy.

 

From our limited testing so far, we can see that there are huge advantages in combining the radio into the main system. Obviously it needs to be managed and correct RT needs to be taught/used. We too have external medics that attend certain performances and as a crew we support other events too. So the vote is "yes". With the right planning and instruction; an invaluable addition to a wired ring.

[sunray]

Currently I wear an ASL headset and the PMR earpiece (Baofeng BF-888s Plus) over the same ear (the ASL only on half an ear so I can still hear stage perfectly).  It can be a little uncomfortable at times.

For a particular job where sound op was in a noisy place, next to boiler and AHU, and wore 'ear defender' style headphones.

 

I made up a little mixer/switch box to easily mix/isolate sound desk and Techpro. IIRC I had to apply the correct load to Techpro to avoid it going unstable.

[sunray]

Just ripped out my last panto, oh yes I have, and can confirm the IEM worked a treat as the base station transmitter on a tecpro system. For the portable transmit side I used a bair of the customers own Baofeng's. Battery life was perfectly adequate for 2 shows.