THSCC Forums

Now that the FM transmitter is operational on 91.1 FM, I have an idea. We've always had trouble getting messages to the pits about worker shifts, meeting announcements, paging people, etc, etc. I know Vincent is working on a "remote speaker" that may or not be ready for use.

In addition to that, let's do the following:

- Those of you with tow vehicles or support vehicles parked in the pits - leave the radio on to 91.1, open the windows, and crank the volume.

- Who's got spare boomboxes at home that can run off batteries? Bring them out, set them up, and help create a pits PA speaker system!!!

If you think you can bring a boombox to try this out, please post here! I think if we had a half dozen or so at each event, we'd probably be able to get announcements out to most of the pits.

I'll be bringing a boombox this weekend.

Thanks!

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

I know when we were down there for the T&T you said that you could pickup that frequency down the end of the runway area we normally use. From the GK area that is pretty good. I tried the same test in my car. I could barely pickup that frequency at the finish of the course with the volume cranked. Let alone in the normal pit area. Granted the radio/car is 13yrs old. But I got music stations down there without problems.

Can most people pickup that frequency loud and clear?

Graham

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http://www.greywinds.com

Graham, At the test&tune I could pick up the station from anywhere on the site as long as I could physically see the bus. Even when down towards the slalom area. My car does have some funky dual antenna setup.

Mike, I will look for batteries for our boombox and bring it for this event.

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In need of car.

Part of the problem with the range is our FM transmitting signal isn't amplified. Most radio stations like WRDU transmit over 100,000 watts...that's a lot of power! I think Mike is working on something to boost the output of the signal.

Another problem is our transmitting antenna does not "break the plane" of the bus. The bus' top is physically higher than the top of the antenna. That limits the range of the transmitter. If we can get the antenna up higher than the top of the bus the signal will travel further. Of course then we will have Ryan ripping off the antenna in addition to the top of the bus!

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Vincent Keene
'06 Ford Mustang GT (track rat)
'15 Dodge Charger R/T (yeah, it's got a HEMI!)
'07 Ford Fusion SE (205,000 miles and counting)
'98 Chevy Z-24 (retired)
'93 Acura Integra (Team SWB 24HOL Car)

But it should be easier to get it higher then the bus top, with that big hole Ryan put in the top of it!

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In need of car.

A few things about the FM trans implementation.

The Ramsey FM-25b is a 25mW transmitter. It's set to full strength, which is technically probably already illegal per FCC regs. Considering we operate at sites where the FCC may already have a keep eye (airports), I don't think we want to look for ways to break into the MegaWatts

With that said, 25mW is the SIGNAL strength, not the LEVEL. Don't get the 2 confused. I think the signal strength is perfectly fine. It worked up to 0.2-0.3 miles in various directions at Lburg. Probably more like 0.5 miles line-of-sight. If we can't get 0.5 miles to a remote finish at Sanford, then we need to evaluate.

Part 2 of this, the LEVEL of the output, is where we have (had?) a problem. The level output of the FM trans was set at anout 1/3. At the rallycross we set it to max. It's much better now - less cranking of the volume knob in your car to hear it.

However, we also discovered that the LINE OUT of the amplifier which plugs INTO the FM transmitter is, for some reason, very, very weak. Rob and I are working on that now.

The goal is basically to have 0.5 mile signal range and a level setting that doesn't require volume to be cranked from where it would be set when you listen to music.

Hope that all made sense.

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

Yes I'm with you on that. Makes sense. When I went from auto tune to manual and dialed in 91.1 I had no problems holding the signal. No real noise or drift. So I think you're transmitting a decent signal. I just couldn't hear the announcer very well.

I also agree at places like Laurinburg, since we are next to the active runway. Let's not have the FCC visit us. That would get us kicked out of there, not to mention fines to go with it...

PS: You guys gotta cut Ryan some slack on the convertible thing. Although whomever did that PhotoChop animated gif for Ryan's sig. Now that was funny

Graham

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http://www.greywinds.com

From my dealings with Airports and radios, as long as you arent messing with the tower or security, they wont mess with you. Our radio transmitter at 91.1 is pretty far away from most airport bands (I know New Bern airport uses 127.x).

Graham, the infamous bus avatar is a joint venture between Jason Mauldin and Mike Westerfield. At first I felt horrible about it but now that all is fixed I dont feel good about it, but I aint beating myself up over it. Whats done is done.

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02 Focus SVT
STF 9

I've got a Portable Radio that I can bring also.

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David Teague
2015 Lexus IS 250c
1994 Honda Del Sol HS 39
2009 Dodge Journey R/T
http://teaguefamily.us

Yeah, I can't imagine an airport comm channel using an RF band. It's just too easy to get interference even if there isn't a tower that close by. Should be fine even if you want to crank up the power some.

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www.ncvw.org
1993 VW Corrado VR6 - DSP15 (RIP)
1986 MB 190E 2.3L 16v - STX (SOLD)
1997 BMW M3 3.2L - BS for now

OK.....I'm going to attempt to answer/reply to several posts within this thread.

1 - The FM transmitter is working fine. The current problem is the amplifier is not providing a "normal" signal level on the line output (i.e. weak signal into the FM xmitter = weak sinal out of the FM xmitter = weak signal on your radio). I verified this Saturday at the RallyX when I bypassed the amplifier and provided a line level signal directly to the FM Transmitter. The signal on the radio in my car was equally as strong as any other station. (NOTE: I only did this for about 1 minute as a test....so any other time during the event, the FM signal would have sounded weak). I'm confident I can have this resolved before this weekend.

2 - The Antenna - We can get another antenna that will transmit further than the current one we are using, but we not convinced at this time that it's needed. Our primary objective was to have a PA system that required no setup at the event. To do this we used a monopole antenna mounted directly on the van and tuned it to 91.1Mhz (1/4 wavelength = ~32 in). Ron made us a dipole antenna that we can use if necessary, but we will have to determine a way to mount it and it will require setup at the event. We'd rather have this as a secondary option to use (if needed) and not as the primary configuration because (again) our objective was to keep it simple (no setup at the event). It's true that we can get more distance if we elevate the antenna higher, but let's see how things work out this weekend at Laurinburg with the current configuration (since will have a strong line level signal being pumped into the transmitter).

3 - Transmitting Power - The FM transmitter has plenty of power to broadcast our signal (0.5 to 1 mile range). Keep in mind, the problem is with the signal coming to the transmitter (not the transmitter).

4 - FCC Concerns - We are not broadcasting in the same spectrum as the airport. While we don't need to modify our equipment to have more broadcast power (as tempting as it sounds....more power..more power!!), don't worry about the FCC coming to hunt us down for what we are currently doing. It's not a permanent setup (we are only at a site for 1-2 days) and we are in such an open area at the site, it's not going to cause noticable interference to others.

5 - Thump/click sound - Many people have noticed a sound (somewhat like a helicopter) in the background when listening our broadcast. We hope to have this cleared up by this weekend. It has nothing to do with the FM transmitter. It's in the signal being delivered to the transmitter (most likely coming from noise on the power rail...possibly caused by the power inverters we are using to power AC devices).

Be patient, I promise we will fine tune the equipment so that it's easy to use, reliable, and something that everyone in the club appreciates. Thanks.

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Rob Harvey
919-697-5485
1997 BMW M3
1992 Acura Integra (Simon)

^^^ What he said.

Thanks for helping clarify Rob!

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1

With an avatar like that, it has to be good!


--Donnie

We are using the same transmitter SCCA uses for national events. In flat areas like Topeka we can pick up the broadcast for a mile or two from the site, so once we have a good signal in I'd expect should be fine. GIGO!

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SPIN or WIN!
there's no glory for going slow.

I was thinking more like -- we're running an unlicensed, untracked, unknown radio transmitter near where operational radio communication can be a life-and-death requirement. I'm just assuming there is a special place in FCC Hell for doing something illegal with a radio ON the airport grounds.

So we're going to maintain a low profile with our nice safe low 25 mW output

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Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1