Please explain diversity

[raqcoon]

I'm considering buying a new Sennheiser G3 wireless lav or a used G2 that's a lot less. I thought that diversity means that both the transmitter and receiver send and receive respectively on two frequencies to keep a constant connection.

From B&H re: Sony: "The receiver features a space diversity design which simply chooses the strongest signal between the dual incoming signals, then sends that signal to output."

But the G3 appears to have a diversity receiver, not a diversity transmitter. Please explain! Where's that second signal coming from? If you have knowledge about any of this and if you have experience using the G3 and G2, any info is appreciated. Thanks.

 

[Richard Crowley]

Diversity is a function of the receiver only. There is no difference at the transmitter end. As the B&H explanation says, diversity is simply the built-in function of a receiver to grab the signal from two different antennas and instantaneously using whichever is the strongest (and presumably best). Note that if you put the two receiver antennas side by side and oriented the same, you aren't really getting any advantage from the diversity function. At minimum the antennas should be 90 degrees from each other, and preferably separated by several feet/meters.

This is basic information about how diversity works. Of course how it is implemented, and especially the sensitivity and selectivity of the dual receiver front-ends will affect performance, diversity or not. And the surroundings, receiver antenna, distance, and transmitter power also affect performance.

 

[Gohanto]

Well, I could be wrong, but I believe diversity is an old, old wooden ship that was used during the Civil War era.

 

[j1clark@ucsd.edu]

I'm considering buying a new Sennheiser G3 wireless lav or a used G2 that's a lot less. I thought that diversity means that both the transmitter and receiver send and receive respectively on two frequencies to keep a constant connection.

From B&H re: Sony: "The receiver features a space diversity design which simply chooses the strongest signal between the dual incoming signals, then sends that signal to output."

But the G3 appears to have a diversity receiver, not a diversity transmitter. Please explain! Where's that second signal coming from? If you have knowledge about any of this and if you have experience using the G3 and G2, any info is appreciated. Thanks.

Two transmitters and two receivers operating on different frequencies would be frequency diversity. As the B&H description indicates the G3's receiver is 'space diversity' unit. One can have transmitter spatial diversity as well... But that's not what the G3 system has...

 

[raqcoon]

Wow, great answers! So there is really no internal frequency diversity, it's a spatial configuration. I don't think that's a big deal, kinda like rabbit ears. I shall reassess my potential G3 purchase.

 

[Richard Crowley]

it's a spatial configuration. I don't think that's a big deal, kinda like rabbit ears.

Diversity IS a "big deal", and no it is NOTHING like "rabbit ears". Each antenna is connected to a separate receiver (TWO antennas, TWO receivers). You have completely missed the point.

One of the biggest problems with UHF (and even VHF) wireless transmitters is blocking and "multipath" reflection from the local environment between transmitter and receiver. Especially when the transmitter is moving around. Diversity has been proven to be VERY effective in combating these problems.

 

[Allan Black]

Well, I could be wrong, but I believe diversity is an old, old wooden ship that was used during the Civil War era.

'IS' ?? you mean it's still afloat .. amazing.

With respect to the thread, its participents, mods and descendants of the crew of the Diversity.

Cheers.

 

[John Willett]

I'm considering buying a new Sennheiser G3 wireless lav or a used G2 that's a lot less. I thought that diversity means that both the transmitter and receiver send and receive respectively on two frequencies to keep a constant connection.

From B&H re: Sony: "The receiver features a space diversity design which simply chooses the strongest signal between the dual incoming signals, then sends that signal to output."

But the G3 appears to have a diversity receiver, not a diversity transmitter. Please explain! Where's that second signal coming from? If you have knowledge about any of this and if you have experience using the G3 and G2, any info is appreciated. Thanks.

There are two types of diversity "true diversity" and "antenna diversity".

Both types use a single transmitter transmitting to a receiver.

In true diversity the signal is picked up by two antennas. These feed two separate receiver modules. These output to a comparator that sends the strongest output to a single output stage.

In antenna diversity the signal is , again, picked up by two antennas,. But this time the comparator is after the antennas which feed the strongest signal to a single receiver module and output stage.

The Sennheiser G3 mains receivers are true diversity and the small camera (pocket) receivers are antenna diversity. The small receiver is too small to fit a second RF section inside the body, so they have to be antenna diversity.

I hope this helps.