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Lectro Dual Sra


JCC

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Hi.

I'm at the Super Bowl and at freq coordination:

1. I chose 4 freq's on block 24 that were on the same page of the bl 24 freq chart. At night, at home, away from any crowds, one freq is stepping on the other, even tho it's on the chart. Is that normal?

Ch 05 steps on Ch A7, but they're both on same page of bl24 freq chart.

I thought this chart was designed to avoid that kind of problem - is that normal for freq's to interfere with each other even tho they're considered safe for each other on the chart?

2. Since one of my freq's (A7) is dirtied by 05 (05 sends a full signal to 'A7'), I'd like to kill A7 and turn my dual sra into a single Rx.

My understanding is that I do this by choosing div mode and selecting ratio (rather than switched), right?

The Rx is showing freq ch 30 (what I set as Rx ch 1) as the Rx freq. I assume that means that since I set it to ratio, the whole Rx is operating on Rx ch1- freq ch 30, and ch2 is moot- no longer on screen, so no longer programmed in Rx - is this correct?

But when I program it this way, I get the message to check my RX2, and half the signal (the right side of signal triangle) is still showing movement from ch 05 (I.e. Still acting like ch 2/freq A7 is on play).

What am I doing wrong? How do I set my dual sra to just pick up ch1/freq05, and put ch2/A7 to bed?

Thanks.

Sent from my iPhone using Tapatalk

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re: sra

 

you seem bang on in your settings.

 

when you switch your div mode to ratio only one display should show up so it looks like a 411 display.

 

if some of your txs are stepping on each other it makes no difference what the receivers are set to. unless the offending tx is also turned off its going to register.

 

using an sra in a seriously heavy wireless traffic situation like the superbowl may really bone you. no front end tracking.

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Sra/b show a warning message when one of the rx channel frequency is set within 4.5mhz of the other channel.

In ratio mode, the antenna display shows the activity of the a/b antenna.. It's not still picking up that other frequency.. It's just experiencing drop outs on that antenna.

My guess is that something/someone else is using that frequency in block 24. Here in az 24 is nearly un-usable.

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This is most puzzling, in more than one way.

 

First, it does seem odd that a transmitter on 05 should interfere with a receiver on A7, especially registering full scale on the meter (if that's what is meant by "sends a full signal").  My expectation would be that you'd have to have the antennas touching to have even a chance of that, as the IF filters are quite effective 16 MHz off frequency.  [besides that, Larry F. pointed out to me just now that it is normally only necessary to use compatible frequencies when more than two units are in use.]

 

Second, once the receiver is in RATIO mode, the two internal receiver sections are supposedly always tuned to the same (single) channel.  The behavior described in this thread makes it sound as though the second receiver were still acting independently.

 

Because I'm the firmware guy, and this sounds very much like misbehaving or mismatched firmware, I'd be very interested in the answers to these questions.

 

1. Is the unit marked on the housing as SR, SRA or SRB, and what is the serial number?

2. When the unit powers on, does the firmware say SR, SRA or SRB, and what version number is displayed?

 

Also, it might be interesting to repeat the 05/A7 experiment, but with different frequencies, to see if the interference changes with channel 1 tuning, channel 2 tuning, or stays the same regardless of tuning.

 

I'll monitor this thread eagerly for any more clues!

 

Fanatically,

David

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David Thomas,

Thanks for being eager AND helpful! - I had to wait to get home to reply to you (and test the gear).

1.  Both are Dual SRA5P's on bl 24  sn's:  65356, and 65189

2.  SRA v1.4 and (v 1.5) bl 24

 

3.  different tx (sm rather than smqv) same block - 2nd Channel also gets full bars on RX when sm is also on ch 05.

     different rx same block - same problem.

 

ch 05 is dirtying both SRA's, and it doesn't matter whether I'm on an sm nor smqv.

ALSO - it dirties a lot of freq's on Both SRA's on Ch 2.

 

Both SRA's show half bars when sm or smqv is at 06, and show full bars at 05, and decreases again around 02 or 01.

 

Still hoping to use these approved freq's this week...

Please let me know if you have any ideas.

 

John

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Hi JCC,

you may have missed it, but post #7 above is from one of the tech guys at Lectrosonics, (he was a little subtle in saying who he was so it might have slid by)  I think you may be well advised to check his post and reply to his questions!

 

Cheers,

Brent Calkin

Next time , he'll send dancing girls waving a banner. (Yes, it was easy to miss).

LEF

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JCC: " Sent from my iPhone using Tapatalk "

you could use the phone part of the iPhone to call Lectrosonics,

they could talk/walk you through it, for best results...

 

mradlauer:" Ratio = single channel, both antenna tune to same freq... Switch = dual mode, each antenna tunes to separate freq. "

I don't think so...

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JCC, thanks for writing back.  Those firmware versions are stable and mature, and matched to your hardware, so I'm left having to venture further afield in my guesses.  [by the way I had to read your first serial number three times to convince myself it wasn't 65536.  I see that number a lot, since it's 2 to the 16th power.]

 

It might be interesting to try reversing the roles of receivers 1 and 2.  Admittedly, there is a guideline that says the Rx2 frequency should be higher, but quoting Dr. Peter Venkman from Ghostbusters, "Actually, it's more of a guideline than a rule."  The rule is that relationship 4.2 <= (Rx1 - Rx2) <= 4.8 (MHz) must be avoided.  The easiest way to avoid it is to make sure that Rx2 is higher than Rx1, but you can also ensure that the difference doesn't fall within the 4.2 to 4.8 MHz range.  In this case, 05 and A7 should present no problems either way.  If system performance is markedly different with the roles reversed, the call is coming from inside the house... woops my movie quoting has gone into overdrive.. I mean the problem is provably internal to the receiver.  If the performance is roughly the same with the roles reversed, we still can't eliminate possible external signals mixing with your transmitters, at least in theory.  Either way we'll learn something useful.

 

Oh, here is another question.  With both the 05 and A7 transmitters switched off, what does a scan of the block look like (using the SRA's SCAN function)?  If it's interesting, perhaps even post a photo if you can conveniently take one.  Ooh ooh!  Then turn on 05 and scan again, for comparison.  That would be very interesting.

 

Okay, cue the dancing girls and/or dancing lobsters.

 

Fanatically,

David

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JCC: " Sent from my iPhone using Tapatalk "

you could use the phone part of the iPhone to call Lectrosonics,

they could talk/walk you through it, for best results..

I heartily enjoy following problem solving threads on this group. Especially when manufacturers directly contribute. I would have a considerably smaller memory index of problem solving techniques if the go-to for our community was *Hat*.

Thanks for not go-to hatting everyone!

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mradlauer:" Ratio = single channel, both antenna tune to same freq... Switch = dual mode, each antenna tunes to separate freq. "

I don't think so...

Senator..You're and "educator", Have you ever heard the term paraphrasing?

 

Is this better? Or will you find something wrong with the Lectrosonics manual?

 

DIVMODE

The SWITCH diversity mode (dual channel mode) allows

the two internal receivers to operate independently

on different frequencies and settings with two different

transmitters. Diversity reception uses an antenna phase

switching technique on each receiver. When this mode

is selected, the setup screens will prompt you to select

the receiver to be adjusted.

The RATIO mode combines the two internal receivers

to pick up the same transmitter and mix their audio

outputs for ratio diversity reception. Diversity reception

mixes the audio outputs in a ratio panning mode. In this

mode, the setup screens will prompt you for a single

value which will automatically be set for both receivers

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Thank you, David. While the senator was hatting me, I did discover (thanks to the phone part of the iphone - which, by the way, makes for a great little computer, but a kinda crappy little phone) that when I put that pesky 05 on ch 1 in the bag, my problems go away.
Higher Math is NOT my strong suit, so I'm not sure why that happened, but I can lift heavy things. ...if they aren't too heavy.
So I'll try the swap and get back to you. Thanks again.


Sent from my iPhone using Tapatalk

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I'm not sure what hatting is, so I hope I'm not doing it inadvertently, or if I am, I hope I can be good at it <grin>.  In any case, the deal with the antennas and receivers is this.  Both antennas always feed both receivers.  In the RATIO case, the antenna combinations are fixed, nominally "in phase" for one of the receiver sections and "out of phase" for the other, so the likelihood of a drop-out affecting both receiver sections is minimized.  In SWITCHED mode, each antenna phase combination switch is under microprocessor control, in an attempt to make preemptive switches before a drop-out gets noisy.

 

Fanatically,

David

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