I thought maximum inclemecy meant that when ever you wanted to experiment with an outdoor antenna, the weather always goes bad 🙂
Sometimes it seems that all I need to do is start winding a matching coil and the bad weather starts rolling in 😀
Thanks for the update!
Experimental broadcasting for a better tomorrow!
My boss likes the idea of using these for IFB in the studio since they are small and relatively cheap. So at some time in the future I'll probably order a pair to test. Enclosures that can hold a battery will be the harder part to find, not much in the way of circuitry to do what I need to do, it's all in the data sheets.
SCWIS,
Perhaps it is a regional thing but here we use it to describe the weather at the time the antenna is erected. In other words, the worse the weather when you install the antenna, the better it works.
It was cold and raining when I placed the tx. near my mailbox so maybe that is why it worked so well. I put the 12V battery, doppler unit, transmitter, and antenna in a plastic storage bin for this test. Seems the 10.25 GHz. and 930 MHz. signals go right through the plastic, though for the final assembly I am looking for something more elegant for packaging..
Greg,
I am using the Linx receiver evaluation board presently for these tests and connected the audio output to an amplifier/speaker that I had built years ago for such purposes. The LM386 amplifier IC provides plenty of gain and output volume with only a few outboard parts. I don't know if you will need amplification if you are using an earphone but thought I would mention this in case you do.
Neil
I was planning on using the amp since the drivers for the ear pieces can run a pretty high impedance, and then it makes a volume control a little easier to add in. Though looking at tha application notes, I'm not sure why they show what they do. They show a pot dropping the level going into the amp instead of running the signal back into the inverting inout to cancel out the output, which is far more common.
Greg,
I recommend you follow the app notes. If you look at the data sheet under "Gain" you will read that the amplifier is compensated for gains greater than 9. It could oscillate if you reduce the gain as you described.
I have built many amplifiers using the circuit shown in the data sheet and never had a problem.
Neil
radio8z is right, I've used the circuits on the data sheets (or even the back of the rat shack hang card 🙂 back when LM386s were sold in the retail stores) and I've also had good luck with the circuits here ICAmps.pdf
Experimental broadcasting for a better tomorrow!
Perhaps take some cues from the hams. Find out what ham repeaters use for STL links and adopt them to part 15 apps. For those who are unfamiliar with ham repeaters, the owner or trustee can remotely control the repeater with his handie talkie using certain codes. Surely these programs can be adapted to part 15.
Side note, one approach to a STL is to use a DTMF or coded FM link. Say broadcast your signal on 88.1 on FM and you have a FM receiver at the part 15 AM transmitter tuned to 88.1, with a adaptation one could use the DTMF/coded approach where you can set it up that only your 88.1 would open the part 15 using the coded signal and then just contunue to use 88.1 as a pure STL link.
Wireless 802-G is yet another approach using WAP encyption, but now we are talking adding a computer directly at the part 15. It could be done though. Wireless G has interesting applications as one can use a high gain antenna to direct the signal to the part 15.
Kyradio,
It has been a few years since I was involved with ham repeaters so things may have changed since then. The predominant means of controlling or linking repeaters was on the 440 MHz. ham band which requires an amateur radio license. The restriction against music and the ID requirements for amateur radio would apply and therefore this would not be suitable for part 15 "broadcasting".
The rules stated that the control link must not be on the input frequency of the repeater, hence for 2 meter repeaters, the 220 and 440 MHz. bands were popular. I used a land line with DTMF to control my repeater.
Part 15 allows the use of 10 MHz. microwaves for proximity sensing (such as door openers). There is available a "Gunnplexer" transmitter and hams have reported Q5 links of 6 miles line of sight with a 15 mW. unit. FM is easy using the built in modulator diode but receiver design can be a bit tricky. These units will tune to the part 15 10 MHz. band but I don't know if the field strength or the application is legal. I thought I would mention it in case someone wishes to pursue it.
So far the 930 MHz. link I described earlier is working great. I haven't done any drive-arounds yet to determine the range, but it works for what I am trying to do.
Neil
What I was referring to was the capability of within the same frequency band ( on the input) to control the repeater ( say 2 meters) in the same fashion one would open the autopatch and get weather, temps, and voice readout of the power of the repeater using the same 2 meters to accomplish this.
Not all repeaters use 440 or 222 for links to control the transmitter, the input on the two meters is used for this. I have seen a repeater trustee control the repeater just using his 2 meter handheld.
For none hams, repeaters are duplex. The functions for controlling the autopatch and the coding is done through the input and the output is squelched so that no one can pick up the tones.
Using this reasoning, one could come up with a basic DTMF signaling system for controlling a transmitter in the same band on the same frequency is the STL link. ie: Simplex
Where as 2 meters is duplex, We could go SIMPLEX on the STL it is feasible to put a sensing circuit with a DTMF decoder in the STL receive on the part 15 transmitter using the same STL feed frequency as the audio is on.
It doesn't have to be used on the the FM broadcast band as a STL link, any frequency thats legal to use would be fair game. But instead of using two separate STL frequencies to do the audio link and the telemetry, one could do both functions on one STL link ...using techniques as the ham ops use.
Kyradio,
In response to:
What I was referring to was the capability of within the same frequency band ( on the input) to control the repeater ( say 2 meters) in the same fashion one would open the autopatch and get weather, temps, and voice readout of the power of the repeater using the same 2 meters to accomplish this.
These functions are not repeater control in that they do not provide for shutdown if the repeater is operating beyond technical limits or if the content is not legal. Autopatch depends upon the integrity of the users and the vigilance of the control ops. As a control op, my concern was illegal content and I have shut my system down when this occurred.
Using this reasoning, one could come up with a basic DTMF signaling system for controlling a transmitter in the same band on the same frequency is the STL link. ie: Simplex
I am not sure what reasoning to use. There are many ways to control a remote transmitter but I was referencing amateur radio repeaters where the rules are specific and which rules do not apply to part 15 "broadcasts". I don't really know why a part 15 operator would need to remote control their transmitter, but if they so desire you and I have provided the key words.
For part 15, DTMF could be used, PL sub tones could be used, as could a variety of signalling methods, but again, why?
On part 15, anything goes as far as control and modulation. This is not true for amateur radio and to try to extend amateur radio rules to this doesn't work in my opinion. I repeat my opinion that amateur radio rules and operation are not consistant with part 15 operation.
Neil