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Jamming

April 5, 2016, 7:34 am
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"Jamming" is the word used for deliberately interfering with another stations transmission by broadcasting loud buzzes or noises to crowd out that station's programming, so that listeners can't hear it properly.

Jamming has been done between countries for decades, and still goes on today.

Of course a Part 15 legally operated radio station could not jam licensed stations in their area, but when can "jamming" be legally done by a Part 15 station?

My first idea from a few years ago was to transmit a buzz saw jamming-type signal on an open frequency just for fun, not actually jamming anyone.

Lately we've been hearing a lot about pirate broadcasters actually using frequencies within listening distance of legal Part 15 stations, and there is no reason why a Part 15 station couldn't "jam" the pirate, of course only within the small area legally served by the Part 15 operator,

The subject of jamming came to mind because that's the topic of this week's "Media Network Plus" from PCJ Radio.

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Compressor and/or limiter

April 12, 2016, 8:08 am
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I am looking for a volume leveling unit for a Part 15 FM transmitter.  The level of the songs varies somewhat and I would like to have it level without spending a whole lot of money.

Has anyone used either or both of these products?  Or, any opinions on these?  They are quite inexpensive, but would it (they) work on my xmitter?  Any ideas or suggestions would be appreciated.

http://www.bhphotovideo.com/c/product/759277-REG/rolls_sl33b_stereo_prog...

http://www.bhphotovideo.com/c/product/746460-REG/Nady_DIGICOMP_16_DigiCo...

Thanks.

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Your opinion counts broadcast vision axs-fmt transmitter

April 12, 2016, 8:31 pm
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I have a chance to get a broadcast vision axs-fmt fm transmitter for $ 25.

Your opinion counts, is this a good buy? What are some possible applications? 

Any mods or hacks? 

Thanks 

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Unexpected Carrier Current

April 13, 2016, 7:57 pm
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We have talked about this in the past, how sometimes our little AM transmitters induce a carrier onto the power lines even though some of us use a radiator and are not intentionally coupling a signal to the power lines via , well a coupling unit.

Since moving to 1620 AM , our coverage has doubled a bit. The weather has been horrible lately, mostly just windy , rainy and just plain miserable to do any kind of work in the yard, that includes the outdoor antenna for AM 1620.

Despite the crummy weather, i have had a chance to listen on the car radio while making our way to town for some grocery shopping and I have been pleasantly surprised by a very nice clear signal for nearly a 1/4 mile from the house, maybe even further than that!

I really don't understand how this can be working so well considering the following conditions involved, you see as long as the listener is in their car or house they have a really good chance to hear Blue Bucket Radio on 1620 AM. Especially if the listeners radio is close to the power lines or better yet, the radio is plugged into an AC outlet. The key is they have to be within view of the power lines which follow the main road that branches off of my short no outlet road.

The conditions in the house, the SStran AMT3000 is using the short wire antenna provided in the kit, the transmitter sits on my desk, the antenna runs up the wall for 2 feet before making an inverted L across the ceiling. The ground (black wire) is not connected to earth ground, it just hangs off the back of the desk.
The only grounding i can think the transmitter is using would be the connection made through the power adapter and the audio chain.

In fact the outlet i am using gets it's power from the house wiring that runs the length of the house to the bathroom which is towards the back of the house at probably 80 feet total length from the studio to the breaker panel in the bathroom. Weird Huh?



Included is a map of the area my signal can potentially cover and if you download the map and enlarge it, you can see where the house's and roads are but it's not that easy to see the power lines. Some of the power lines weave in and out , near the road in some places and then back behind a few houses before going back out to the road and eventually meeting up with 4 huge transformers, from there the power lines go North and disappear into the hills.

I doubt the signal passes through the transformers considering those things put a loud buzz in any radio close to them.

I really hope this isn't some kind of a fluke and continues to reach out there beyond our road, for a good idea what i am rambling on about, view the attached map, download it too for a bigger view. If you download the map, you can zoom in to get a better idea how things are laid out here.

I think 1620 is going to work out just fine for Blue Bucket Radio.

WOW I did not use spacing or even create separate paragraphs...geez.

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Mystery Ticking On AM Upper Sideband

April 26, 2016, 5:12 am
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One day not long ago I began noticing that if I de-tune an AM radio to the upper carrier edge of my 1550 kHz transmission I distinctly hear a "tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a-tick-a" that just goes on and on without variation.

There is no hint of this ticking sound on the center-tuned main-carrier nor on the lower sideband.

The transmitter is an AMT3000 from sstran(dot)com modified to work with a hand-wound loading-coil and Wintenna (metal window in-line with half-indoor half-outdoor vertical antenna ground clamped to basement I-beam below the floor.

Turning the transmitter audio control to zero the ticking sound stops, therefore suggesting that the sound is introduced from the 25-foot audio cable which runs from a computer audio output to the transmitter audio input.

Sending silence from Winamp over the 25-foot audio line results in the same ticking sound.

By software-disconnecting the audio feed from the 25-foot audio line does not change the ticking sound.

Viewing the silent carrier on the spectrum analyzer shows no artifact produced by the ticking sound.

The ticking sound is not interfering with another station because it is not far enough out on the side-band to reach another channel, it's in the "splash-zone" of the main carrier.

The ticking sound is not causing an actual problem... it's just "there", but naturally I'd like to discover what's causing it to happen.

I'll be examining it from time to time, but also seek your input about what might be taking place. If it happens to me it could happen to others, so we need to establish a "cause-solution" file.

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Got the Whole House FM 3.0

April 26, 2016, 10:00 pm
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I know I havent posted hear in some time but I will be trying out some new test since some of you were interted in that tin foil experiment I did with the TV atenna. 

I got the Whole House 3.0 and I am happy with it. Only downside is you will need a compressor to get some good quality audio. They did advertise for a while it had a AGC but reading some revies and the manual I dont see anything about a AGC.

Anyways back to my point I will be trying that tinfoil test again with thease transmitters and see the range I will get. I did test it with the Talking House but there was no effect and I get around .5 - 1 mile's with it so I am happy with the range I get. 

 

I will post on this topic my results but just a question to keep it part 15 does the tinfoil and TV atenna increase the feild of strength or is it just boosting the signal?

 

Thanks :)

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The HB Transmitter Test

April 29, 2016, 6:39 am
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Looking back at the results I think it may be useful to both sites if the actual field strength observations could be published. For example, at the measurement distance what was the field intensity for the Rangemaster set at 100 mW and so on. Comments?

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Shielding Multiple Wireless Mics

May 16, 2016, 9:34 am
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PLL Problem Solved

May 19, 2016, 3:19 pm
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A few years back I built a phase locked loop circuit very similar to that of Tom Polk which is linked here: http://www.tompolk.com/radios/frequencysynthesizer/freqsynth.html My circuit topology was the same but some of the component values were different and this is not meant to be critical of Tom's design since his may or may not have the problem noted below.

When on the air with this PLL I noticed a background noise which sounded a bit like a wind whistle in a car and was especially apparent when listening to the carrier on a receiver set to CW mode. Typically, such noise is caused by phase jitter (phase noise) and this was confirmed by viewing the lock signal on pin one of the 74HCT4046 with a scope. There was over 1 microsecond of peak to peak jitter and on the spectrum analyser there appeared a strong subharmonic of the carrier at about 580 kHz.

I did a bit of homework and found this site: http://www.sm0vpo.com/ which is linked from Tom Polk's site. On this site follow projects> synthesizer circuits> improved CMOS synthesizer to find a schematic of a similar circuit. The author shows a schematic with a different loop filter connected to pins 9 and 13 of the 4046 which he claims narrows the skirt on the spectrum for the synthesizer. Since the phase jitter I saw would result in a wider skirt I thought it worth while to try this loop filter so it was installed in my PLL and the noise is now gone. The jitter is now less than 40 nanoseconds peak to peak and is inaudible on the transmitter signal and there is no longer a subharmonic in the spectrum.

If you are using or going to build this circuit it seems beneficial to use the loop filter shown on Harry's page.

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Testing continues here....

June 4, 2016, 2:22 pm
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I haven't posted in a while, too many other things going on.  I have been playing with my TH5, and as I reported several weeks ago, was doing some inductive transmissions using the neutral line with limited success.  Worked pretty well up to a couple of blocks then just dropped out completely.   Tried several other things, no other gains noted.

Of course it has been raining here almost continuously.  So I haven't been able to get much done outside.

Today, I took time to move my TH5 to a small truck tool box that is weather proof, mounted a 102 in. whip on the box, and mounted the TH5 in it.  Ran power cables, patched in the wireless link etc.   It is about 25 foot high on a metal roof, not my preference, but it is what I have available.

Range is about the same so far.  Maybe a little more uniform in pattern since it is not dependent on the transmission lines for reception.  And I am still fighting a hum.  It is prevalent all over town, so I do not think it is the TH, it does of course couple with the signal, but I have got it minimized somewhat. It is not my feed system, as it doesn't exist when I use my FM transmitter, which BTW sounds great, but isn't what I am focusing on.

I did get the sound quality to come up on the TH5 by using an old mixer I had with equalization.  Actually getting some depth from the transmitter now.  

I had to quit for the day, because we have T-storms coming again, and my wife wants me to take her to dinner this evening (she has some nerve..LOL).

Will tinker with it tomorrow probably weather depending, and report back.

Wish me luck..

 

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Talking House THII Question

July 14, 2016, 12:00 am
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Not really a technical question but here goes

What is a decent/good price for a lightly used Talking House TH II AM transmitter.

Follow up.... If I can get said transmitter at a good price, is it a good xmitter to get my feet wet in AM broadcasting?

Any and all input appreciated

Thanks

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Appears to be certified

July 18, 2016, 8:07 am
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On Board Processing

July 18, 2016, 2:12 pm
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Another website published some incorrect information about the AMT3000 and AMT5000 transmitters with regard to their on-board audio processing.

The author mistakenly claimed that the on-board audio processing on the two SSTran units cannot be disabled, and so defeats any advantage from an outboard audio processor.

The truth is just the opposite. Let's take a tour.

Both the AMT3000 and AMT5000 have a built in compressor which can be set between 1:1 and 5:1. Perhaps what the author at the other site doesn't know is that "1:1" means "no compression". When the control is turned fully counter-clockwise the compression is disabled, which of course allows full un-hapered use of an outboard audio processor.

Another control, the modulation control, is in fact a limiter. When set according to instructions it prevents overmodulation no matter how loud the input is set. Most transmitters don't have a built-in limiter, and they can easily be over-modulated UNLESS an expensive outboard limiter is added and calibrated, but sound quality is no different doing it one way or the other.

Be careful what you believe unless you read it here at part15(dot)us.

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New LPFM shows up near Deltaville What?

July 21, 2016, 8:44 am
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WWND 103.9 a LPFM statation was granted a license in April of THIS YEAR information found here:

 

http://radio-locator.com/info/WWND-FL

 

Don't get me wrong I love this stations spirit as they really do serve what is missing from commercial Radio and I really support these guys. I'll listen too and see if they are looking for any help as well.

 

I stumbled upon the station when I was doing my routine tests to see if my transmitter was interfering with other stations down the dial. Found WWND and at first I thought they were Pirate and here is why. Their promo's faded way too soon into the music. Then I heard an older gentleman say WWND Kilmarnock. Really I thought that is 6 miles from me. So I did the digging to see what was up and found this out.

 

I've only lived here since January 18th of this year and if I had been here long enough I may have found that someone was looking to put up an LPFM station that close to me and could have LEGALLY been a part of this. At least it would allow me to learn and catch up on some of rusty skills I have acquired.

 

What puzzles me is why was the license granted in April of 2016 and the window has been closed for sometime? Is there something we were not informed about? I might have been able to join his group and if he has other programming could have had an Album Rock segment legally going that range I wanted and it would have been Hobby Radio alright for this town.

 

Now I need to somehow be friends with him and most likely get more serious about AM here as to not cause any sort of interference to his station in an apartment right next to mine. I sure hope these guys have great success. Hats off to them.

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Broadcast Vision FM Transmitter on Ebay

July 25, 2016, 7:06 am
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Indoor Multi-Path

July 26, 2016, 9:21 am
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The very limited range of FM part 15 makes it practically useless for reaching out to a neighborhood, but there are indoor uses for micro-FM transmitters.

Two uses, for example, are sending an FM signal 35-feet room-to-room out to an SSTran AMT5000 for re-transmission on the AM band which does reach into the hood.

2nd use is sending FM 6-feet over to a radio for editing audio.

The big bug-a-boo is multipath, those unwanted signal fade-outs in with blasting noise-static pops blowing voice-coils.

You think you've got it fixed for a week and suddenly it's back, proving conclusively that there are evil entities intent on wrecking our peace.

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Definite Stands

July 28, 2016, 6:10 am
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At this time during this election season I wish to take definite stands on certain transmitter issues.

The FM Rule 15.239 is nonsense. It is nonsense for two reasons. Nonsense Reason No. 1 is that anyone goofy enough to attempt doing something with so weak a transmitter is obviously not able to verify that the field strength meets 15.239. Nonsense Reason # 2 is that the only way to get a solid, multipath free signal using a 15.239 transmitter is to locate it one-foot from the FM radio. The sillyness of 15.239 falls on the FCC.

Carrier Current is dangerous. Radio hobbyists should avoid experimenting with AC powerlines in hope of reaching several extra feet with an AM radio signal. If a member of your family insists on dabbling in carrier current get a big fat life insurance policy on them and there's a good chance you will come into some money.

Only three Part 15 categories deserve full attention:

15.219 AM band broadcasting, 15.217 Long Wave broadcast, and 15.225 Short Wave Radio.

Those three Part 15 categories are worth pursuing for the increased range they provide and being alive for the experience.

In closing may I say the FCC is not your friend. They have jobs, they don't want you causing work.

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How To Be Heard

July 29, 2016, 3:45 pm
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There are a few households within range of my AM contour, and if I really wanted to increase the liklihood that one of them would find my station, I would put transmitters on every open frequency and literally hog the dial.

Of course people who ignore AM would be in their own culturally deprived world. 

If possible, I might put an FM transmitter on a pole at the property line adjacent to their window.

If you like this idea and plan to do it join this thread and report your progress.

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780 New Stations! Pick Your Spot With Care!

July 31, 2016, 5:24 am
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That Night That Tower

August 1, 2016, 7:39 pm
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In a year that no longer exists I was on the 19th floor of a bank building in a downtown area with a 400 foot tower rising above me with blinking red lights.

During a lengthy symphony record I followed the steps to the roof door and climbed to a platform about 20-feet up the base of the tower.

From there the Mississippi River was clearly in view including barges and river boats floating around.

At that moment I realized what life was truly about. But I'd not thought to bring a pen or paper to the experience and cannot remember.

 

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