Can't find a reliable channel in NYC

vladwolodarsky

vladwolodarsky

Active member
The other day on a shoot I was using a Sennheiser G2 set and I ran into an issue where the audio would drop out for a half second every 10 seconds or so. I tried to different xlr cables and 2 different mics, so I know it wasn't a cable issue. I was in the middle of Manhattan and I couldn't use any of the available frequencies from the senn frequency finder since the G2 range doesn't cover the available frequency range. I think the issue I ran into was related to finding a solid frequency.

Would a Senn G3 set be more reliable since it covers a different frequency range? Please try to forgive me for some basic oversights. I'm a videographer doing ENG work and advice will be greatly appreciated.
 
Yeah, the G3 will "probably" work better. But what's really important is to find out what bands are most commonly clear in the areas you are most likely to be using them in. Obviously you know that - I just mean that step should always come first - then buy. Buy according to your frequency slots.
 
It's difficult to say what your problem was. Things can change from one minute to the next.. even my $3k Lectros are not any wheres near problem free. I use Lectro 211/411 on-board scanner, (or a stand-alone one) and always find open slots in Sennheiser block A (512-554 MHz) and Lectro block 21 (537-563MHz) frequently, even in Times Sqr. (RF hell) but as I stated, it can change quickly, especially on the street. Inter-system modulation gets really complicated when you have to change though with multiple systems
BTW, the G2/3 on-board scanner is useless IMO.
 
Rick R said:
Things can change from one minute to the next.. .
Click to expand...

I guess depending on the radio activity in the area? And maybe even the weather?

How would you suggest finding a solid frequency on a G2 set without the on board scanner? It looks like the stand alone scanners are really expensive. And the available freq in the area outside of the g2 range.

Thanks for your help! I really appreciate it.
 
"depending on the radio activity in the area?"
- Yes sort of, not broadcast radio per se. primarily TV and other local activity causes interference and 'RF hits'.

"And maybe even the weather?"
- I don't think so, except a thunderstorm.

"How would you suggest finding a solid frequency on a G2 set without the on board scanner?"
The Sennheiser frequency finder is a good place to start, if you understand the numbers, however finding a fully vacant channel (in the Sennheiser blocks) is unlikely for the NYC area..There are smartphone apps as well to ID legal FCC broadcasters in a specific area.
Otherwise, pray to the RF gods.. and/or manually checking the receiver for a clean bank/channel (w/ transmitter, pilot tone and squelch off) (BTW, what block is your G2?)
There's other ways to stack the cards in your favor as well. Search here and other pro audio discussions for tips.

As I recall, the H/H RF Explorer is about $125 cheap.

- Addendum: FYI, the newer G3 EK100 portable receiver has a diversity antenna system.. but that alone would not really help your frequency selection/interference issues either. It does have slightly wider frequency blocks though as well as other niceties.
 
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Thanks again for your input. This is really helpful.

The G2 set is in the 518-554 block. I'll have to try doing a freq scan with pilot tone and squelch turned off. I'll also start searching for smartphone apps too.

I checked again and for the 10022 area code the available frequencies are 698-806. From what I've seen the G3s don't cover that range. This sony set only covers 698. But does that mean that 698 is totally vacant and there wouldn't be any issues?
 
These days if you are serious about using radio microphones you need one of these http://rfexplorer.com/models/ for just over a $120 it can save you.
RF listings are useless as they are only fixed location Tx units and don't take into account the random use of the RF spectrum by others like the local news service or PA companies etc. You need REAL TIME checking.

How did you did you do a scan on your G2 unit? or was it just trying different frequencies rather than a scan?
 
OzGizmo said:
How did you did you do a scan on your G2 unit? or was it just trying different frequencies rather than a scan?
Click to expand...

I did it on the G2 receiver when the transmitter was off. I scrolled through the sub menus until it said scan and it saved I think 4 different frequencies.
 
"I'll have to try doing a freq scan with pilot tone and squelch turned off"
That won't help, by manual I mean you have to tune to a channel and see if the RF indicator is illuminated, if it is, tune to the next until you find the RF indicator extinguished, then listen for extraneous noise. If it's clean, reset the squelch and PT, switch on the transmitter and tune that to same freq. Unfortunately this is laborious and time consuming, but there are few other options.
I checked out your area (Midtown East, also an RF hell) and found some possible frequency ranges to try out for your Sennheiser A-block G2.

Tune to some frequencies within TV channel 26 (542-548MHz) in which the maximum Prx level is -67.0dBm (attenuated @ -30) from WYXN-LD.

The next possible frequency range to try are within TV channel 22 (518-524MHz) which has a Prx of -66dBm.

Another possibility is within TV channel 27 (548-554 MHz) which maxes out at -65dBm from WTBY-TV in upstate Poughkeepsie (aka, 'Poughtown' to locals).

My preferred target level is around -80dBm/Prx or less, but your options here are few.
In any case, tune your receiver to a frequency within one of the available TV channels above and confirm the receiver's RF indicator is NOT illuminated. (with the transmitter off). If all is good, then tune the transmitter to the same frequency.. and away you go.
 
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vladwolodarsky said:
I checked again and for the 10022 area code the available frequencies are 698-806.
Click to expand...


I think those frequencies are unavailable. The 700-800 MHz UHF was auctioned off to telecom use.

The Sennheiser frequency finder seems to be using stale data, since this 'clearing' of the spectrum occurred quite a while ago.

The next big shift is for the above 600 MHz band... so the recommendation is to buy equipment that can operate lower than 600...
 
"I think those frequencies are unavailable. The 700-800 MHz UHF was auctioned off to telecom use."
--- For sure, and are illegal at this point

"The Sennheiser frequency finder seems to be using stale data, since this 'clearing' of the spectrum occurred quite a while ago"--
-- The 'data' itself is directly from the FCC (in the US), (when the FCC website is down, there was no data on the Sennheiser frequency finder, as was the case last year the the gov. agencies were temporarily shut down), how the Sennheiser website interprets the data is another story.
The 600MHz block is scheduled for auction this year (allegedly.... since it's been postponed numerous times) I don't think those frequencies will be 'illegal' to use for a few years after the auction happens.

In any case the OP's G2 (A block) can only tune to frequencies within 518-554 MHz in 25-kHz steps... a total of 1440 I recall.
 
Rick R said:
"I think those frequencies are unavailable. The 700-800 MHz UHF was auctioned off to telecom use."
--- For sure, and are illegal at this point

"The Sennheiser frequency finder seems to be using stale data, since this 'clearing' of the spectrum occurred quite a while ago"--
-- The 'data' itself is directly from the FCC (in the US), (when the FCC website is down, there was no data on the Sennheiser frequency finder, as was the case last year the the gov. agencies were temporarily shut down), how the Sennheiser website interprets the data is another story.
The 600MHz block is scheduled for auction this year (allegedly.... since it's been postponed numerous times) I don't think those frequencies will be 'illegal' to use for a few years after the auction happens.

In any case the OP's G2 (A block) can only tune to frequencies within 518-554 MHz in 25-kHz steps... a total of 1440 I recall.
Click to expand...

In the case of 600 MHz, unlike the 700+ MHz band, if the channel is currently 'unused', I think the FCC allows for 'use' by mics (as well as White Space Devices). I don't have the text in front of me, but that's what I recall.

There's a whole lot of pressure on TV broadcasters to share channels or move down out of the 600 band... so this is not just a 'mic' user issue.
 
What was only slightly mentioned is that you are in probably the worst place possible for wireless. The Broadway shows fire up hundreds if not thousands of of wireless mics and intercoms, plus every body else like news and film crews. In that RF hell I would definitely get the real scanner because nothing else is really going to give you a picture of what is open at that moment where you are. The fun will really begin when they loose the 600 block.
 
Hi all,

Thanks again for all of your help. When I was running errands yesterday I did a test outside of the same location. I know that the conditions are going to change every day, but I thought it was worth trying out.

I tried out Rick R's tip of manually tuning to freq to see if the RF light is NOT illuminated. The RF light was ON for all of the freq he recommended.

Next I tried a scan on the receiver and it said 0 channels free. Surprise! I tried out the last freq saved during the scan and it actually worked perfectly even though the scan said it wasn't totally free.

I guess my takeaway is to get a real deal RF scanner.

Do you think that the new rodelink system could fix this problem? From what I understand it's going to operate on a different spectrum??? I'm not a sound guy! I'm just a videographer who has to run audio every once in a while.
 
vladwolodarsky said:
Hi all,

Thanks again for all of your help. When I was running errands yesterday I did a test outside of the same location. I know that the conditions are going to change every day, but I thought it was worth trying out.

I tried out Rick R's tip of manually tuning to freq to see if the RF light is NOT illuminated. The RF light was ON for all of the freq he recommended.

Next I tried a scan on the receiver and it said 0 channels free. Surprise! I tried out the last freq saved during the scan and it actually worked perfectly even though the scan said it wasn't totally free.

I guess my takeaway is to get a real deal RF scanner.

Do you think that the new rodelink system could fix this problem? From what I understand it's going to operate on a different spectrum??? I'm not a sound guy! I'm just a videographer who has to run audio every once in a while.
Click to expand...

From a quick look... the Rode Link uses 2.4 GHz... which is 'full' of WIFI, Bluetooth, Mircowave Ovens... whatever.

I don't know what the technical details on how Rode is doing their digital transmission, so I can't say how much this may affect things. From the glossy brochures it seems they are naming their RF signaling, "Series II, 2.4 GHz".

Have no idea what 'series II 2.4 GHz' may be. There's also mention of two channels, and frequency agility... again don't know what that may mean either...

802.11 devices can, depending on the device, operate at 5, 10, 20, 40 MHz bandwidths. Bluetooth hops around the 2.4 spectrum. So Rode could use some custom signaling that gets around certain problems with 802.11 or Bluetooth. Perhaps a custom spew mode with heave forward error correcting...

But as with all RF devices... testing is in order in 'bad conditions' to see if it will work as reliably as one needs... can accept...
 
Disabling the squelch all together likely would show 'some' RF and trigger the indicator in NYC. Sorry for he confusion. Try it on 'LOW' (the default setting), the 'Pilot Tone' would still be off though. I would still look for a frequency within the TV channels mentioned, there are many to choose from. Using the manual 'Tune' function, some or your own presets can be saved in the 'U' (user) bank. A scanner is still almost a necessity around here. (NYC)
I have no experience with any of the 2.4 GHz systems.
 
Thanks guys! My RF Explorer showed up in the mail today. I watched some basic tutorials and I've been tested it out in my apartment. I'm surprised that I am getting some RF hits with with a freq that's at -100dBm/Prx. I'm planning on reading the entire RF explorer manual.
 
I've done some more tests and I'm still getting RF hits with freq that have a prx level of -100.

I've poked around the rf explorer site and google and I can't find the right info. Do you know of any spectrum analyzer tutorials?
 
vladwolodarsky said:
I've done some more tests and I'm still getting RF hits with freq that have a prx level of -100.

I've poked around the rf explorer site and google and I can't find the right info. Do you know of any spectrum analyzer tutorials?
Click to expand...

What do you mean 'RF Hits'. Is that when you set up your wireless mic, you still get interference, in the form of a brief cutting out of your audio?

While I just briefly looked at the RF Explorer web page, it may only show RF signals that have a 'long/continuous' duration. At the price, I suspect there is that sort of limitation.

However, in order to get a 'real time' spectrum that includes the capability of capturing 'brief' pulses... one can expect to pay 10's of thousands... (I was 'amazed' at the amount of wyrd signals out there after we got our $80K+ Rohde and Schwarz analyzer... as in 'what the hell was that???'...).



In any case, it seems you can narrow the bandwidth to 2 MHz, which is less than a 6 MHz TV channel, but greater than FM signals used for typical 'audio'. (While TV broadcasters have switched to digital so there would not be an FM audio signal with most TV broadcasts, there may be low power or other licensed use in the area...)

Does the device have a 'peak' mode vs 'average' mode, and that may give some clues... but again the device has to be 'fast' enough to capture short duration pulses.
 
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