Simple RF tracker

Here are some details of my little pet project I’ve been working on in preparation for the coming season. It may be of some interest to someone. The idea was to build a simple RF transmitter to track small rockets. It had to fit into 19mm or smaller tube and weight less than 20g.

The attached photos show the result. It does fit snugly into BT-20, has length of 105mm and weights 16g. I used a 430 MHz transmitter-receiver pair sold by Maplin (in the UK) as VY48C for £10 (https://www.maplin.co.uk/transmitter-and-receiver-pair-22965). Both transmitter and receiver are manufactured by RF Solutions and can be bought from them directly , though £25 minimum order is required. The leftmost element on the board is the transmitter. The input signal is provided by a simple generator on 555 IC (about 3 KHz in Mk1 design).

The third photo shows the receiver. Again, nothing fancy. Very simple design with output to headphones or a buzzer (not seen on the photo. It’s on the box side).
Antenna is a very simple Yagi design (https://www.iw5edi.com/ham-radio/?cheap-yagi-antennas-for-vhf-uhf,93).

Last weekend I had a very good chance to test the system. Deployed payload was tracked and eventually recovered using only instrumental observation some 1400 meters down the range from the launch site.

JNUK said:

Here are some details of my little pet project I’ve been working on in preparation for the coming season. It may be of some interest to someone. The idea was to build a simple RF transmitter to track small rockets. It had to fit into 19mm or smaller tube and weight less than 20g.

The attached photos show the result. It does fit snugly into BT-20, has length of 105mm and weights 16g. I used a 430 MHz transmitter-receiver pair sold by Maplin (in the UK) as VY48C for £10 (https://www.maplin.co.uk/transmitter-and-receiver-pair-22965). Both transmitter and receiver are manufactured by RF Solutions and can be bought from them directly , though £25 minimum order is required. The leftmost element on the board is the transmitter. The input signal is provided by a simple generator on 555 IC (about 3 KHz in Mk1 design).

The third photo shows the receiver. Again, nothing fancy. Very simple design with output to headphones or a buzzer (not seen on the photo. It’s on the box side).
Antenna is a very simple Yagi design (https://www.iw5edi.com/ham-radio/?cheap-yagi-antennas-for-vhf-uhf,93).

Last weekend I had a very good chance to test the system. Deployed payload was tracked and eventually recovered using only instrumental observation some 1400 meters down the range from the launch site.

Click to expand...

That is very nice, how much do you have in all of your set up?
TX/RX pair is great that you can buy them together, most of the DIY trackers ive found are much more - work - .. making your own tx.

Very nice, thanks for posting, i enjoyed looking.

Thats quite cool, but what about the reception? It advertises 70m range, which is not particularly useful for rockets. Did you amplify it somehow?

Very interesting, what other kind of electronics did you solder to the breadboard? Do you have a circuit diagram?

Cyril's Scribe said:

Very interesting, what other kind of electronics did you solder to the breadboard? Do you have a circuit diagram?

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I didn't keep a record of all bits, but all together it was about 30 pounds or so including the receiver box.

ClayD said:

That is very nice, how much do you have in all of your set up?
TX/RX pair is great that you can buy them together, most of the DIY trackers ive found are much more - work - .. making your own tx.

Very nice, thanks for posting, i enjoyed looking.

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It's a very nice system, but 433.92 MHz is a Region 1 ISM band and can not be used in the US.

• Region 1 comprises Europe, Africa, the Middle East west of the Persain Gulf Including Iraq, the former Soviet Union and Mongolia.

https://en.wikipedia.org/wiki/ISM_band https://en.wikipedia.org/wiki/International_Telecommunication_Union_region

Bob

Lentamental said:

Thats quite cool, but what about the reception? It advertises 70m range, which is not particularly useful for rockets. Did you amplify it somehow?

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The transmitter is indeed not very powerful. The distance you mentioned is at the right scale although I would say it about 100...150 meters for transmitter down on the ground. The increase is due to additional gain the Yagi antenna provides. However, and this is the key, then the transmitter is up in the air the link loss is significantly less. Based on calculations and field tests it can be tracked descending some 1000....1400 meters away (at least) using the pair receiver.
If the transmitter descents at the distance over 150...200 meters away from the receiver, the signal will be more likely lost when it's down, but it'll be possible to find it following the flight path.

bobkrech said:

It's a very nice system, but 433.92 MHz is a Region 1 ISM band and can not be used in the US.

• Region 1 comprises Europe, Africa, the Middle East west of the Persain Gulf Including Iraq, the former Soviet Union and Mongolia.

https://en.wikipedia.org/wiki/ISM_band https://en.wikipedia.org/wiki/International_Telecommunication_Union_region

Bob

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How about 315 Mhz? There are similar modules for that band https://www.rfsolutions.co.uk/acatalog/4_Pin_Transmitter_Modules.html Propagation will be even better.

bobkrech said:

It's a very nice system, but 433.92 MHz is a Region 1 ISM band and can not be used in the US.

• Region 1 comprises Europe, Africa, the Middle East west of the Persain Gulf Including Iraq, the former Soviet Union and Mongolia.

https://en.wikipedia.org/wiki/ISM_band https://en.wikipedia.org/wiki/International_Telecommunication_Union_region

Bob

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I've just checked specs for 868Mhz version (https://www.rfsolutions.co.uk/acatalog/DS013-8-AM-RTx.pdf) which I believe Region 2. Its output power is +7dBm comparing to 0dBm for 433 MHz. These 7 dB of extra power will compensate for increased link loss due to higher frequency. The link distance will be approximately the same for both variants. The drawback is that the transmitter power consumption is higher reducing the battery life. Also it requires slightly more stable power supply.

Bob, yes.. i was curious about the cost, because everytime i endevour my own stuff, i spend way more than i think i will...
if he is at 30 pounds, i think this would cost me around 75.00...(no real conversion just what i think i could build one for.

I have looked up a lot of home built trackers. and they simply look painful to build.... but this is something i could build with my son since the TX and RX are paired. takes a lot of "stuff" out of the game.

the Telemetrum uses a frescale 433 70cm band. i would probably just use the same band.(i think)
I know those guys have linked the packets over 20,000feet. Also know guys who say they cant track but a block...edit/// its not freescale its by texas instruments.-Frequency range: 300 – 348 MHz, 391 – 464 MHz and 782 – 928 MHz


The matched tx/rx gives a little more stability.

JNUK said:

I've just checked specs for 868Mhz version (https://www.rfsolutions.co.uk/acatalog/DS013-8-AM-RTx.pdf) which I believe Region 2. Its output power is +7dBm comparing to 0dBm for 433 MHz. These 7 dB of extra power will compensate for increased link loss due to higher frequency. The link distance will be approximately the same for both variants. The drawback is that the transmitter power consumption is higher reducing the battery life. Also it requires slightly more stable power supply.

Click to expand...

866 MHz is a European band, however the duty cycle of a transmitter in this band is limited to 1%. With the duty cycle limitation, battery power is not an issue.

https://cellphonesafety.wordpress.com/category/868-mhz/

It a cell phone band in the US so that out here as well. The equivalent US band is 902–928 MHz but power in this band is limited to 1 mW.

https://en.wikipedia.org/wiki/ISM_band

https://cellphonesafety.wordpress.com/category/868-mhz/

Bob

Bob, using a transiever that is matched... isnt that no different than using a wifi port..?
My point being that no you cant go buy a handleld brodcast vocie... but cant a scientific device, like texas instruments makes, transmit on those frequencies...?? since they do the fcc licensing...

ClayD said:

Bob, yes.. i was curious about the cost, because everytime i endevour my own stuff, i spend way more than i think i will...
if he is at 30 pounds, i think this would cost me around 75.00...(no real conversion just what i think i could build one for.

I have looked up a lot of home built trackers. and they simply look painful to build.... but this is something i could build with my son since the TX and RX are paired. takes a lot of "stuff" out of the game.

the Telemetrum uses a frescale 433 70cm band. i would probably just use the same band.(i think)

I know those guys have linked the packets over 20,000feet. Also know guys who say they cant track but a block...edit/// its not freescale its by texas instruments.-Frequency range: 300 – 348 MHz, 391 – 464 MHz and 782 – 928 MHz

The matched tx/rx gives a little more stability.

Click to expand...

Well you are known to want to overbuild stuff just a tad......

The comments in my first response addressed unlicensed use in the US. If you have a HAM license I think you could use the 433 MHz device. device.

Here's a link to the US RF Spectrum Allocations.

https://www.ntia.doc.gov/osmhome/allochrt.pdf

Here's a link to the FCC Redbook which lists all the frequencies and transmission and equipment requirements for radios in the US (10 Mb)

https://www.ntia.doc.gov/osmhome/redbook/ed200801rev201009/Manual_Sep_2010.pdf

Performance in the microwave reqion is highly dependent on your circuit layout. Unless you understand the specialized methods involved, you are better off buying modules commercially. You certainly can make the above mentioned boards on a one-off basis for the selling price.

My first stop on any electronic project is https://www.sparkfun.com as they probably have a module to do what you want or something close.

Bob

ClayD said:

Bob, using a transiever that is matched... isnt that no different than using a wifi port..?
My point being that no you cant go buy a handleld brodcast vocie... but cant a scientific device, like texas instruments makes, transmit on those frequencies...?? since they do the fcc licensing...

Click to expand...

I'm not sure I'm following your train of thought, but digital data is digital data. So within legal uses of wifi and wifi transmitters, if you have a microcontroller in your rocket and it's connected to a FCC licensed wifi modem, you could communicate with another wifi device such as a notebook, netbook or even Ipod Touch or Ipad running the right software.

Again. Check Sparkfun.

Bob

The thread name was bugging me so I edited it to "tracker". If I am missing something (a very real possibility) and it actually should be "tracket" let me know and I'll change it back with apologies.

bobkrech said:

The comments in my first response addressed unlicensed use in the US. If you have a HAM license I think you could use the 433 MHz device. device.

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Provided you meet requirements in terms of transmitting your callsign, etc.

-Kevin

call sign requirements are simple, you can transmit with your handheld even if your "rocket" equipment isnt... But if your transmitting data, the devices like telemetrum, and i think big red bee let you put your callsign in it.

Nevermind that your handheld will not transmit as far as your rocket at 20k...

Bob - no one is ever on my train of thought... you should know by now.
The ISM wikipedia thing just confused me... I didnt understand it.

I do overbuild, and I am thinking of making a toilet paper rocket just to have a test of my shredding ability..(a guy who just put two 16"x10'-0 sections of sonotube in the corner-its glaring at me..)

Making flashcards for my ham test... ( i will never get through reading that book...) next test is on 6-5, so i may not have a call sign before nebraska heat...

Back to the OP.. My son graduated kindergarden today... so a tracker would be a great fun summer thing to do with him... we have a little darkstar, and some woods by the house, that would be great fun to play "rocket" hide and seek.

A good thing in this thread is the prebuilt tx.. i never thought about putting that on a board, and driving it with a 555, i have a few 556's i never got around to using. usualy, normal rockets i can get within 100 meters of where they are.. so i dont need anything that goes 1500meters.

(my J1000 i want to fly... hopefully i can find a loaner LL electronics 6XL to fly in it) that needs at least 1500meter reception....

§ 97.119 Station identification.

(a) Each amateur station, except a space station or telecommand station, must transmit its assigned call sign on its transmitting channel at the end of each communication, and at least every 10 minutes during a communication, for the purpose of clearly making the source of the transmissions from the station known to those receiving the transmissions. No station may transmit unidentified communications or signals, or transmit as the station call sign, any call sign not authorized to the station.

Click to expand...

I’m sorry for the confusion. I didn’t know it’s so much more difficult in America. For once it seems to be much easier on my side. There are no any specific licence requirements for the 433 MHz band assuming low power of course. Also there are no any requirements with regard to a transmitter duty cycle as long as its output power doesn’t exceed 0dBm. That’s is why I used that particular model.

The Sparkfun.com was mentioned by Bob. I’ve checked it and found this 315MHz transmitter https://www.sparkfun.com/products/8945 . It seems to be close to the one I use although I’m not sure whether it’s AM or FM. Does the band require license as well?

JNUK said:

I’m sorry for the confusion. I didn’t know it’s so much more difficult in America. For once it seems to be much easier on my side. There are no any specific licence requirements for the 433 MHz band assuming low power of course. Also there are no any requirements with regard to a transmitter duty cycle as long as its output power doesn’t exceed 0dBm. That’s is why I used that particular model.

Click to expand...

No need to apologize -- you came up with a neat little project that should prove quite useful to you.

It's just a matter of folks needing to understand and comply with the laws of wherever they're flying.

-Kevin

troj said:

§ 97.119 Station identification.

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Soo... how do you operate a becon transmitter that doesnt brodcast a callsign?

JNUK said:

I’m sorry for the confusion. I didn’t know it’s so much more difficult in America. For once it seems to be much easier on my side. There are no any specific licence requirements for the 433 MHz band assuming low power of course. Also there are no any requirements with regard to a transmitter duty cycle as long as its output power doesn’t exceed 0dBm. That’s is why I used that particular model.

The Sparkfun.com was mentioned by Bob. I’ve checked it and found this 315MHz transmitter https://www.sparkfun.com/products/8945 . It seems to be close to the one I use although I’m not sure whether it’s AM or FM. Does the band require license as well?

Click to expand...

Theres very limited bandwidth that doesnt require the license. Serisoulsy, someone like me can make some flash cards take a test.. and have a license.

Again, thanks for your post. doing something like this will simplify it...

ClayD said:

Soo... how do you operate a becon transmitter that doesnt brodcast a callsign?

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That's yet another reason why the Walston type beacons are not operating within the current regulations and laws.... How do you operate a beacon transmitter that doesn't broadcast a call sign? Legally, you don't.

n5wd said:

That's yet another reason why the Walston type beacons are not operating within the current regulations and laws.... How do you operate a beacon transmitter that doesn't broadcast a call sign? Legally, you don't.

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There's a "group" of falconers in my area, a lot of them use becon transmitters that dont transmit call signs.
they say that it is not required... the do this in the middle of the city)... Being, there are many more manufacturers than just Waltson trackers that currently dont brodcast a callsign, and are still manufactured.. surely someone thinks they are legal.. You mean the "band of brothers" hammy's havent turned these guys into the authoriti??

surely youve seen waltsons operated, i know i have,, Have you not reported them?

(and i thought you could send you tracker to waltson and have them program your callsign??)

No one can tell me what i am doing is illegal, except for the law..... thats the way i see it.

n5wd said:

That's yet another reason why the Walston type beacons are not operating within the current regulations and laws.... How do you operate a beacon transmitter that doesn't broadcast a call sign? Legally, you don't.

Click to expand...

It all depends on the frequency used and the purpose. On the amateur bands, except as noted, a callsign is required.

CFR 97 covers the amateur bands.

CFR 47 covers wildlife and buoy tracking, so tracking falcons with the frequencies covered is allowed, without a callsign.

However, rockets are neither wildlife nor buoys, so those frequencies are not valid for rocketry in the US.

-Kevin

troj said:

It all depends on the frequency used and the purpose. On the amateur bands, except as noted, a callsign is required.

CFR 97 covers the amateur bands.

CFR 47 covers wildlife and buoy tracking, so tracking falcons with the frequencies covered is allowed, without a callsign.

However, rockets are neither wildlife nor buoys, so those frequencies are not valid for rocketry in the US.

-Kevin

Click to expand...

I certainly think thats tit-for-tat. Beyond what i would look at,, in a falcon over rockets....(as far as the callsign is considered). I would gamble my retainer fees on it. I will never succumb to the idea, one person can take liberty that i cannot simply because one is a rocket, and one is hunting. I doubt i will ever have to defend that. This is just a small glich when one tries to make rules for the exception.

Most of the becons , and even GPS telemetry, dont transmit an audible callsign, that means if you dont have a decoder you arent getting the transmitted callsign anyway.
So if someone is using a becon with a data packet, and i only have a voice reciever how am i supposed to be able to identify them, i think that is the sole purpouse of the call sign anyways. is to identify the person using the equipment.

If you sending to aprs (thats another story...) I am talking only about becons.


Being you have to have a license to own a falcon, and faa waivers for rockets... i think the usage is so small and miniscule, its a rediculous non issue to bring up.

Cornell has a neat article i found a while back, was the one i deemed too expensive..


https://courses.cit.cornell.edu/ee476/FinalProjects/s2008/eky2_cc459/website/index.html



Standards and Legal Considerations
Our designs conformed to all the applicable standards. The most important being the FCC’s regulations on radio frequency communications. It does not interfere with any licensed transmitters and operates solely in the range of unlicensed band 433MHz in accordance with Part 15 of the FCC regulations on wireless devices. According to FCC, we need to get authorization if we plan to sell this device or if we make more than 5 of them. Since neither are the case, we do not need FCC authorization.
Dont they have a good lawschool... maybe i should apply!

ClayD said:

surely youve seen waltsons operated, i know i have,, Have you not reported them?

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Yes, I've seen people operating Walstons and no, I've not dropped a dime on them. I've got enough problems making sure I do things correctly to worry (much) about someone else and what they're doing.

ClayD said:

(and i thought you could send you tracker to waltson and have them program your callsign??)

Click to expand...

If you can, that's news to me. If I remember correctly, some of the Comm-Spec units can be programmed with a callsign... the Beelines come with the callsign embedded, but as far as I know, the Walston units don't have the ability to transmit a call sign.

ClayD said:

No one can tell me what i am doing is illegal, except for the law..... thats the way i see it.

Click to expand...

Stick with that policy, Clay. It's doing you good.

ClayD said:

Being you have to have a license to own a falcon, and faa waivers for rockets... i think the usage is so small and miniscule, its a rediculous non issue to bring up.

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But it's still against the law no matter how ridiculous you may think it is. We can get away with a lot of things if we want, but that doesn't make it right.

Greg K7RKT

bigredbee said:

But it's still against the law no matter how ridiculous you may think it is. We can get away with a lot of things if we want, but that doesn't make it right.

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But that means letting What's Right get in the way of what you want, Greg!

-Kevin