Cancun Wireless Problems. HELP!

[Matt]

Hello,

 

I am working in Cancun, Mexico and am having all sorts of wireless issues.  Does anyone know of a good resource for TV frequencies in use down here?  Anyone else experienced problems down here?

 

We are using Lectro WM transmitters with Venue Systems.  When we do a scan it comes up clean, but with the good frequencies set, we are barely getting any range with 250mW transmitters.  Intermod is clean, too.  But, as soon as we go out in the field, there are all sorts of problems.  There is a cell tower within a 1/4 mile of the area we shoot in.  Obviously, this may be the core issue, but I don't know. 

 

Any help is appreciated.

 

-Matt

[jacefivesound]

What's the venue/antenna setup? Have you tried putting the transmitters in a lower power mode? How many 250mw txs are you using, and what are their proximity to each other?

[Matt]

We tried a lower power mode (100mW), but got even less range.  They are pretty spread out.  I'd say varying from 2 feet to 50 feet throughout the day.  Problems occur regardless of distance.  Venue is using a pair of dipoles.  It is like everything is being stepped on by something, but the scan shows nothing.  We are having the same problem with 411 bag receivers set to the same frequencies as the Venue receivers.

 

-Matt

[ben lowry]

Matt,

Just found some spectrum notes from last time I worked in Cancun (about a year ago).

- only active TV broadcasts were analog and VHF (ch 5, 7, 11, 13)

- very strong taxi dispatch centered around 475.250 MHz (within TV ch 14 & Lectro block 470)

- 450 - 470 MHz (commercial walkies, etc. in the US) had many very strong but intermittent signals

- UHF that covered Lectro blocks 19 to 26 was completely open over the week I was there

 

So, if you're doing a coordination & have a spectrum analyzer that will do peak-hold, let it run for a while to find those strong lower-UHF intermittents, which may be giving you surprise intermod products that the Venue scans miss.

 

Hope this helps. Who knows what has changed since a year ago?

 

Ben Lowry

[jason porter]

411's and the Venue show clean scans?

Are you using whips on the 411's? or tapping into the Venue antenna distro?

[LarryF]

Try taking a transmitter and a receiver on batteries, by themselves (no other gear, at all!) a half mile away from the set and see what the range is. If the interference is TV or cell or...., it won't change much. If it is some other gear on the set, the added distance will make a big difference. It sounds as if you are getting hit by wideband noise that is at a low level but is everywhere.

Best,

Larry F

Lectro

[stevegrider]

Are there any video transmitters on set? If so, are they in close proximity?

[Ed White]

@ Ben,

Great post. Much good info. Probably won't help Matt on this shoot, but which peak hold spectrum analyzer are you using?

Best,

Ed

[ben lowry]

Hi Ed,

My favorite is the WinRadio WR-G33WSM, but it requires using a laptop running Windows (in my case by running Parallels on my Mac). I also have a TTi handheld unit, whose scan files can import directly into IAS software and is much more portable, but the WinRadio gives me a better big-picture idea of the spectrum. I haven't really played with the newer (very inexpensive) RF Explorer to know how good it is.

Ben

[Matt]

Thanks guys. We are using 411's in bags with whip antennas, and Venue rack mounted with 2 systems tied together and hooked to a pair of dipoles. Blocks 21 and 22.

Larry, what is the minimum operating distance we should use a 250mW transmitter with the 411's? I'm wondering if they could be "splattering" RF across the block. We're using 6 of them per block. Total of 12. Using LecNet and scanning for clear frequencies up to 7th order intermod and they are clean. We see nothing on the scan when we use the Venue scanners, but still are getting distance issues and poor RF performance even at short distances. Tried 100mW but it was even worse.

Matt

[John Steigerwald]

How long/what type are the cables on the dipoles?

 

How high do you have them?

 

Is the range on the 411's any better than the venues?

 

If you turn off all Tx (including IFB, hops, etc) except for one is there any improvement?

 

Are both venue frames wideband?

 

Is the antenna power in the venues set to off?

 

Are you working with coordinated frequencies?

[LarryF]

Thanks guys. We are using 411's in bags with whip antennas, and Venue rack mounted with 2 systems tied together and hooked to a pair of dipoles. Blocks 21 and 22.

Larry, what is the minimum operating distance we should use a 250mW transmitter with the 411's? I'm wondering if they could be "splattering" RF across the block. We're using 6 of them per block. Total of 12. Using LecNet and scanning for clear frequencies up to 7th order intermod and they are clean. We see nothing on the scan when we use the Venue scanners, but still are getting distance issues and poor RF performance even at short distances. Tried 100mW but it was even worse.

Matt

There is no minimum distance in that people are using transmitters in bags with separation distances of 6 inches. Granted, it takes some frequency co-ordination and some frequency separation. Let me be blunt. Until you try my earlier recommendation of moving a test rig away from the set, you are whistling in the dark.

Again---<<<Try taking a transmitter and a receiver on batteries, by themselves (no other gear, at all!) a half mile (or even a quarter mile) away from the set and see what the range is. If the interference is TV or cell or...., it won't change much. If it is some other gear on the set, the added distance will make a big difference. It sounds as if you are getting hit by wideband noise that is at a low level but is everywhere.>>>

Best,

Larry F

Lectro

[twmmps]

John (and everyone)

 

The dipoles have 50 ohm BNC cables. One rig has single run 40ft. lengths that work from 8-10 ft. high for close proximity to 30ft. high  for long range reception. (Outdoors & Mobile) The other rig works on 25 ft lengths either single of doubled run using BNC barrel in a house interior at 5 ft. high.

 

The 2 racks have Venues. The house has 12 units in standard racks block 21 & 22 with 6 each block in each rack. The mobile  rack has 18 units in blocks 21/22/27 with six in each block. 2 are wideband units and one is regular standard rack. Antenna power is off.

 

Freqs are IAS coordinated and verified white spaces with scans in Venue software and on 411a field scans. 

 

I would say the 411's have much less range than the venues. 

 

We have used the WM's on 250mW and 100mW and the is not much perceived benefit at 250mW. A small gain in signal strength but not as much as seems there should be . Also when WM at 250mW is used in same scenes with 100mW 400 body pack the signal of the 400 is as strong or stronger than the WM. The WM seems to be underperforming. In many cases the 411a bag receivers cannot get more than 30 ft away from the transmitters before serious signal strength issue. 

 

Based on past shows with the same setup using 400 series transmitters I have to say the WM's are a bit of a disappointment. They don't seem to perform in some cases as well as the 400's, and they get really hot to the touch. Which leads to the whistling issue Matt has talked with you all about.

 

Thanks to all who are helping here.  T 

[bralleput]

2 years ago I did a TV drama where on every location I did a 411 scan (no problems on the set freq.) BUT after videovillage powered up my block would be full with undefined RF.Could not use ANY wireless.Turned out that the (consumer)video village HD monitor (that was about to break down) was spraying all this RF.Could this be the cause?