Boat to Shore Wireless Audio

[ihalevi]

Hello.

In a few weeks we will be producing a live broadcast of a rowing event (which we do every year). The entire production is based off a launch (motor boat) following the race from start to finish. We stream the production from the boat using a bonded cellular solution.

We just got a request to also broadcast the commentary audio from the launch to the finish line at the shore, so that spectators could listen to it. We can't get the commentary off the video stream, since it will be noticeably delayed from real-time.

Any ideas out there for ship to shore wireless audio transmission?
The feed from the commentators on the boat is line-level.
There is a speaker set up on the shore.

There is no power on either side. So both transmitter and receiver need to be battery powered.
Max distance is about 2 miles.

I was thinking of maybe a two-way radio, but not sure which one has audio in and audio out.
Any other ideas?

Thanks!

Imry

 

[TJCornish]

2-way radio quality SUCKS. If there is cell coverage, I would use a pair of cellphones with appropriate audio in/out adapters.

 

[MRW Lights]

There is an audio company Zaxcom out of NJ that makes sound equipment for use in film and television that has the longest range I know of, but that's only 1/2 mile. The suggestion of the cell phone is your best bet, JK Audio makes a few adapter packs and a bluetooth version... but your audio quality isn't going to be amazing. RODE makes an Iphone ready mic that is fairly deccent and Sennheiser just announced a new one at NAB, but I didn't catch how soon it will be available.

2 way radio is also dangerous in means of RF exposure limits and subject to rules by the FCC, maybe nothing you need to worry about, but it's definitely something you don't want to have to worry about.

 

[rsmentele]

Neutrik Xiruim! Long distance transmission of two channels of analog, Dante or AES. Battery powered if need be, configurable by phone/tablet if needed. SUPER robust signal. You actually have to be very careful when setting it up as it will completely shut down any frequencies it locks to. And its not too expensive, if you will purchase it. But odds are, you can find a rental set nearby.

The only issue is with that distance you may have to use a repeater midway. Super low latency either way.

http://www.neutrik.com/en/audio/xirium-pro/nxp2tx

 

[FMEng]

It's buried in the fine print, but the range of Xirium is, optimistically, 500 meters. It would take three repeaters to go 2 miles. The system is really designed for fixed, point to point use with directional antennas. I'm not sure how you would reconfigure on the fly as the boat moves and and needs more repeaters. Not a good fit.

This job would be ideal for old Marti RPU equipment, although it would be difficult to power on battery. Given the power problem, I would probably do it via cell phone. If you can get a pair with HD Voice, it could sound fairly good. There are various Bluetooth I/O options to connect mics and outputs for sound systems.

I was going to suggest renting a pair of Comrex Access IP codecs. The problem with that idea is that one end will need a fixed IP address, or both units need to be subscribed to the transversal server. That's not practical in a rental situation.

 

[sk8rsdad]

What about unlicensed an FM transmitter? FCC regulations apply so make sure you know the rules. Any FM receiver can be used to receive the signal.

If money is no object you can look at optical networking solutions (line of site microwave, IR, or laser) and stream the video and audio together with lower latency than your bonded cellular solution. Alignment might be a problem for a moving object.

 

[Chris15]

What sort of environment are we talking about?
In the middle of a large city? In the middle of nowhere?
Understanding the RF environment might render some ideas better than others...

 

[FMEng]

What about unlicensed an FM transmitter? FCC regulations apply so make sure you know the rules. Any FM receiver can be used to receive the signal.

If money is no object you can look at optical networking solutions (line of site microwave, IR, or laser) and stream the video and audio together with lower latency than your bonded cellular solution. Alignment might be a problem for a moving object.

A legal, Part 15 FM transmitter won't go anywhere near 2 miles.

 

[TimMc]

What FMEng said.

There are products that will come close to doing what you want but none of them are available for unlicensed use and the physical things that must be done to have dropout-free coverage will put the project well beyond budget. TV show and movie producers can afford to mitigate the issues but your rowing event is unlikely to.

Cell phones are not my idea of a robust, mission-critical method but will likely be the most budget friendly and legal.

 

[Morte615]

A few ways to help mitigate the show critical part is using multiple cell phones. Buy 4 cell phones from Wal-Mart for $20 each, add on a $15 card and some cable to connect the phones mic and headphones to a speaker (or mixer.) Run 2 phones on the boat, preferably from 2 different carriers if possible, and 2 phones on shore. If one drops just switch to the other.
Still not ideal but probably still cheaper than a licensed system.

 

[Jay Ashworth]

Look for a cellphone app that implements the Opus codec, optimised for broadcast audio. I don't have any app names handy.

 

[ihalevi]

Cell phone it is! Thanks for the help, everyone.

 

[GreyWyvern]

Cell phone it is! Thanks for the help, everyone.

@ihalevi, what exactly did you end up doing and how did it go? Curious minds want to know!

 

[ihalevi]

Hi Dave.

We bought some of the JK gear, but as it turned out the entire setup was changed last minute on the river.

The production was set up on the shore at the finish line. We have a camera on a launch covering the first 1000m of every race, and then a couple of cameras at the finish line covering the second 1000m. Graphics and commentators were added on the shore as well, right by the finish line. So we ended up having a 60' TV at the finish line, which showed the program feed and played out the commentator audio. So...no need for wireless audio.

I hope that makes sense.

Imry