Lectrosonics in an aerobatic plane at 7200 feet.
Charles Tomaras
oriented towards music and sound reinforcement asking me about renting some
wireless gear and the feasibility of using it on a pilot in an acrobatic
airplane performance for air to ground "entertainment." I told him I wasn't
sure how well it would work but I could rent him a 250mw transmitter and
receiver and we also included Larry Fisher in our communication and he
thought it should work reasonably well but also made no implicit guarantees.
Anyway...the engineer, Mark Bader, gave it a shot earlier this week and I
have included his letter back to me about his results. I also believe that
Lectrosonics may write this up for their website and include some photos and
additional information.
Hi Charlie,
Well the airplane test last weekend with the Lectrosonics gear was a
resounding success! We were able to get a good usable audio signal at over
7200 feet! Here are the details:
My client wanted to transmit high-quality audio from his small airplane to
the ground. The aircraft radios have notoriously poor audio quality, and he
wanted to see how well I could improve on that. My idea was to transmit
directly from the headset mic instead of going through the aircraft intercom
system.
On the ground I set up your UCR211 receiver with the two dipole antennas
about 10 feet apart, along with a mixer and some speakers so others could
hear the audio (see photo). On the front of the table is the wiring
harness for the plane. In the airplane, I set up the UM250B transmitter
velcro'ed to the rear seat harness. I tried to get the transmitter as high
as I could to get away from the most metal possible (see 2nd photo). I also
needed to purchase an adapter that converted the aircraft headset mic signal
into a mic-level signal that your transmitter would accept. I am still
looking into better ways to make that connection.
With this configuration, I was able to get about 7200 feet away from the
plane and still get a usable signal. At that distance, there were
occasional drop-outs and clicks, especially when the aircraft was doing
loops and rolls. But the audio quality, and especially the low-end, were
amazingly good. I kept the pilot tone squelch on the entire time, and never
lost the signal. IN FACT, the spectators on the ground mentioned that the
audio was so good, they almost didn't believe that we were hearing the pilot
in the plane, it sounded like someone on the ground with a wired mic.
This is definitely the configuration I will be using moving forward.
By the way, I did end up testing 3 different antenna configurations. With
the whip antennas directly attached to the receiver, I got a steady audio
signal but it had quite a bit of drop-outs and clicks. I then tried the
dipole antennas, that reduced the drop-outs considerably and seemed to
increase overall RF signal strength (however it was difficult to quantify
since the RF meter went up and down with the orientation of the plane).
Then I tried the yagi antenna. This worked very well, however it needed to
be pointed at the airplane to get the best gain, and given the fact that the
diploes worked so well and don't need to be pointed, I went with the
diploes.
Thanks again Charlie!
-Mark
Dennis Haggerty
interesting. Thanks for posting it.
Are those pics up anywhere?
dennis haggerty
Ty Ford
(in article <2bGdnadU_-h8wL7V...@comcast.com>):
> By the way, I did end up testing 3 different antenna configurations. With
> the whip antennas directly attached to the receiver, I got a steady audio
> signal but it had quite a bit of drop-outs and clicks. I then tried the
> dipole antennas, that reduced the drop-outs considerably and seemed to
> increase overall RF signal strength (however it was difficult to quantify
> since the RF meter went up and down with the orientation of the plane). Then
> I tried the yagi antenna. This worked very well, however it needed to be
> pointed at the airplane to get the best gain, and given the fact that the
> diploes worked so well and don't need to be pointed, I went with the diploes.
OK, fine. Now try it at 7200 feet in August in Baltimore during a Bermuda
high when we can't even see the top of the 1200' stick the TV stations
broadcast from because of air pollution!
Seriously though, nice job.
Regards,
Ty Ford
--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU
oleg kaizerman
> OK, fine. Now try it at 7200 feet in August in Baltimore during a Bermuda
> high when we can't even see the top of the 1200' stick the TV stations
> broadcast from because of air pollution!
is it because people start fire on barbeque with pages from your articles ?
vin
maybe, but it is certainly not from gunfire and bombs.
Jason Porter
I wonder if the TX antenna could have been mounted outside of the
cockpit for even better performance!
-Jason
On May 8, 4:09 pm, "Charles Tomaras" <toma...@tomaras.com> wrote:
cmassey
transmitter could have been mounted outside, and the audio cable run
to it. At low speeds, good gaff tape would be fine. But then again,
who wants to experiment and lose a transmitter.
cleve
Charles Tomaras
news:09399e35-43f4-4c71...@a1g2000hsb.googlegroups.com...
> Great story!
>
> I wonder if the TX antenna could have been mounted outside of the
> cockpit for even better performance!
>
> -Jason
Could be, but the plane's fusalage was canvas so maybe centered as it was in
open air inside was the best location given all the twisting and turning.
This was just a test run at an airfield in the middle of knowhere in Eastern
Washington. Mark said that his 211 scan in Block 22 was
flatline....absolutely no interferrence. I'm thinking it's gonna be a bit
tougher when they take this routine to a number of airshows in more
populated locales.
oleg kaizerman
"vin" <sound...@gmail.com> wrote in message
news:ea16a646-767a-4f4a...@l17g2000pri.googlegroups.com...
jeff c
> yes , it probably mixed with furts from the indian food restoants around :-)
>
>
> news:ea16a646-767a-4f4a...@l17g2000pri.googlegroups.com...
>
> > is it because people start fire on barbeque with pages from your articles
> > ?
>
> maybe, but it is certainly not from gunfire and bombs.
Sounds sorta like the PGA tour.... Lots of 250mw xmitters... I'm
surprised the airplanes ignition did not create a big fat wideband
recording of the engine RPMs... ;) Cool!
Steve King
news:ffb17a77-ad82-400e...@j22g2000hsf.googlegroups.com...
All but very early antique aircraft have fully shielded ignition systems, so
ignition noise is rarely a problem.
Steve King
jazzology
<steveSPAMBL...@stevekingSPAMBLOCK.net> wrote:
> "jeff c" <soundmixe...@gmail.com> wrote in message
I had assumed that a strictly aerobatic or racing plane might not have
a shielded or choked plugs on the ignition... given that are not a lot
of nav and comm stuff in the cockpit... hurricane hunters, a
different story, thanks for that tidbit.. ;)
Jeff c
Steve King
"jazzology" <jazzol...@gmail.com> wrote in message
news:78a33bce-1b6a-42ae...@k37g2000hsf.googlegroups.com...
I've not seen an plane without shielded ignition other than true antiques.
If the plane has even a single nav-com (communications tans-rcvr/navigation
receiver), a requirement if operating the aircraft at any airport with a
control tower, it will need a shielded iginition. Even the 1948 Aeronca 7AC
trainer that I first soloed, a two-place trainer with an 85 HP engine, had a
vhf radio and a protected ignition.
Steve King
Steve King