MK4 Sniffer Saves The Day!

[JoeTomasone]

Got a call this morning to assist a UDF team that could not locate an EPIRB.   They had been out for hours last night, and a few more this morning.    When I got there, the team showed me what they were getting with the L-Per - which was inconsistent at best.    Bearings in different places pointed in all manner of directions, and signal was lost/reacquired in several spots.   So, we put the Sniffer to work, and quickly located the EPIRB.   It was in a dumpster.   Between two long metal storage  buildings.   Underneath power lines.   And, to top it all off, the battery was just about dead.   

It was the worst-case scenario for the L-Per.    The Sniffer saw through it all and found it reasonably easily, although I'll admit it was a challenge, mostly due to the (lack of) signal strength.   Even when placed up to the antenna, the signal was only half-strength.   

If you haven't considered the Sniffer before, I strongly encourage you to do so.

[vento]

Good to hear about more success stories with the Sniffer.

I can only wish my Sniffer is also battle tested. Until now, it had seen very little action other than SAREX and UDF mission that had signals ceasing before we arrived. I always carry mine in the car ready to deploy. Our squadron also have a L-Per with the wooden stick and two cheese blocks.

[RADIOMAN015]

At least in my wing the number of ELT call outs has decreased drastically, so there's very little interest in using CAP unit funds to buy this equipment.  HOWEVER, for those also involved in amateur radio DF "fox" hunts this looks like it would be a great piece of equipment. 

It's too bad the inventor could not get the unit to cover 108-1300 mhz, I think this would give it a much broader market and appeal.
RM

[Mark_Wheeler]

What do you guys use for antennas? We have a Miller Enterprise one on ours and it works like a charm.  I've used a sniffer twice on UDF missions and they sure are nice. One problem though if everyone has sniffers, when you run into either 243.0 only or even more rare 243.0/406.025 beacon, your sniffer won't be able to do anything.

Mark

[JoeTomasone]

What do you guys use for antennas? We have a Miller Enterprise one on ours and it works like a charm.  I've used a sniffer twice on UDF missions and they sure are nice. One problem though if everyone has sniffers, when you run into either 243.0 only or even more rare 243.0/406.025 beacon, your sniffer won't be able to do anything.

Mark

I use the discontinued Diamond MAY1000 handheld beam.   

I've yet to encounter a beacon with no 121.5 component.   <shrug>

[Spaceman3750]

I've always been interested in the MK4 but haven't looked into it in detail (especially because I'm not very good with comm-related things besides what's in the 100 series and push then talk).

How difficult are they to build for someone with no electronics/radio experience?

[JoeTomasone]

I've always been interested in the MK4 but haven't looked into it in detail (especially because I'm not very good with comm-related things besides what's in the 100 series and push then talk).

How difficult are they to build for someone with no electronics/radio experience?

You don't build them, you buy them pre-assembled from the manufacturer.

http://www.foxhunt.com.au/

[SARJunkie]

all 406 beacons still transmit a 121.5 homer.

121.5 is a harmonic of 243, so you will receive 243 on 121.5

[Mark_Wheeler]

all 406 beacons still transmit a 121.5 homer.

121.5 is a harmonic of 243, so you will receive 243 on 121.5

Theoretically yes, they should transmit on that as well, but in the cases I've seen, the antenna has been damaged in some way where its cut that its only transmitting anything readable on 243.0. The 121.5 was on as well, but its only able to be picked up 200 feet away or so while the 243.0 was audible for several miles.

[Major Lord]

all 406 beacons still transmit a 121.5 homer.

121.5 is a harmonic of 243, so you will receive 243 on 121.5

Actually, its the other way around: 243 is the second harmonic of 121.5. A " harmonic" is a component frequency of the signal that is an integer multiple of the fundamental frequency.

Major Lord

[Thom]

all 406 beacons still transmit a 121.5 homer.

121.5 is a harmonic of 243, so you will receive 243 on 121.5

Actually, its the other way around: 243 is the second harmonic of 121.5. A " harmonic" is a component frequency of the signal that is an integer multiple of the fundamental frequency.

Major Lord

Yes, and 243.0 can generate a 121.5 signal, which would be the 2nd "subharmonic", or 1/x division of the signal. Note that subharmonics are almost universally much weaker than harmonics when speaking of radio frequency signals. I wouldn't want to depend on catching a subharmonic of a signal in order to track it down, but it is a possibility. Using a harmonic, such as detecting a 243.0 signal (2nd harmonic) from a 121.5 source is much more likely to be useful in real world circumstances.

Fun fact: One of the reasons that Bells are so distinctive in tone is that they naturally generate a core tone (1st harmonic) as well as both harmonics (overtones) and subharmonics (undertones), combining to give that unique sound.


Thom

[Major Lord]

I am not sure if the 121.5 signal from a 243 transmitter is a function of it being a subharmonic, or an incidental radiation of the reference oscillator used to produce the 121.5 signal. Either way seems probable, but I have not dissected an ELT or looked at one on my spectrum analyzer to know how dirty the output is. The spurious output specs look pretty tight as I recall. I suppose that the received 121.5 component could be a function of the wide band AM receiver creating a "Ghost" image by "ringing' the front end of the receiver. And now back to your regular programming....

Major Lord

[vento]

What do you guys use for antennas? We have a Miller Enterprise one on ours and it works like a charm.  I've used a sniffer twice on UDF missions and they sure are nice. One problem though if everyone has sniffers, when you run into either 243.0 only or even more rare 243.0/406.025 beacon, your sniffer won't be able to do anything.

Mark

I use a LVA-1 magnetic mounted from L-Tronics while driving in my vehicle. And a Diamond MAY 1000 out of the vehicle.

[JoeTomasone]

I use a LVA-1 magnetic mounted from L-Tronics while driving in my vehicle.

Forgot to mention that; I have one too.

[ECHO35]

I use a LVA-1 magnetic mounted from L-Tronics while driving in my vehicle.

Forgot to mention that; I have one too.

Hello I was just reading all the posts and if you guys want an RDF unit that is really accurate you should look into the Tigerstrike made by Firestorm emergency services. It makes everything else look obsolete

here is the link:  www.fsems.com

[Larry Mangum]

Hmm, the last poster seems to work for Firestorm.

http://www.socom.mil/sordac/TILO/BusinessPartnerNetwork/Lists/Business%20Partner%20Network/DispForm.aspx?ID=57

[Major Lord]

The MK4 has a wonderful advantage over the Tigerstrike in that it actually exists. I thought that after years of taking peoples' money they would have delivered a product by now.

Major Lord

[SarDragon]

[ECHO35]

As I am new to this forum I was unaware of the past banter between Maj Lord and my fellow colleagues. Upon further review it seems Maj Lord has a axe to grind I wonder why. What ever the case spreading rumors and false information about a company or another person is petty and unprofessional. At the end of the day search and rescue is about saving lives not personal differences.

Here are a few facts:
-The Tigerstrike does exist, I have one sitting next to me
-Tigerstrike has demonstrated to have a 2 degree aperture at 2km
-Can hunt an ELT over 80km
--132dbm sensitivity
-Demonstrated in a recent SAREX with CAP wing in Tampa where it located a ELT at 3.1 nautical miles in 30 seconds
more facts can be found at the website:
www.fsems.com

Bottom line is the proof comes when you see it for yourself and I would be happy to demonstrate the Tigerstrike to anyone who would like to see it.

I am always available if you have questions

Respectfully,

Paul Greaves 910-528-1512

"De oppresso liber"                                                                           

[Major Lord]

Excellent, I am pleased to know its a commercially produced item. Can you tell us the name of the CAP members who were provided the units mentioned on your web page so that we can solicit their experiences? If you would like to bring a unit to Travis AFB, I will arrange to have interested parties attend to see your product.

Major Lord