MISSISSIPPI RADIO DIRECTION FINDING MSRDF FEBRUARY 20, 2021 T-HUNT EXPERIENCES:
We really enjoyed our first experience of a T-hunt during the February 20th event. My wife and I heard about it a few weeks prior and decided to give it a try despite not having any experience or directional equipment. I built a version of WB2HOL’s tape measure yagi for the antenna. My handheld has no S meter and I don’t have an attenuator so I decided to use a SDR (software defined receiver) Nooelec NESDR dongle from Amazon that I had laying around. Combining this with a Raspberry Pi computer and some free software called Cubic SDR gave me the ability to tune, see the signal on a spectrum and attenuate the strength. Our strategy for the hunt was to start near the center of the mapped area and sweep to decide on what quadrant to focus our efforts. The HT picked up a signal near our start area and a quick spin of the yagi indicated a direction up the same road. After a bit of stumbling, we narrowed the area and the yagi even told us which side of the road to search and be the First to Find! The SDR, although a bit cumbersome worked super and we discovered that a tape measure yagi design, if held out the vehicle window above 20 mph, rolls itself into a non-functional mess. Vernon, KI5HGX MSRDF MARCH 13, 221 FOX HUNT EXPERIENCES Fox Hunt March 13, 2021 I had only been involved in one small walking fox hunt before this one but was excited to see how well my home made Yagi antenna would work. I bought an offset attenuator to use with the antenna and since none of my HT radios have a signal meter I decided to use my old trusty Radio Shack Model 95 Pro scanner as a receiver. There is no signal meter but it has a built in attenuator you can turn on and off with a button. My wife and I arrived at the start point, registered and got our instructions. Once the fox left and started transmitting I immediately got a strong signal and a general direction. Once we were freed to pursue I would find a strong signal and take a bearing using the SigTrax app on my phone to try to get enough bearings to triangulate once the fox stopped moving. We spent some time driving around and taking signals. I made a mistake with the SigTrax app and accidentally deleted all my bearings I had taken (and not saved as I should) so I decided to go old school and do it by ear. The transmit signal from the fox was very strong and covered a large arc of direction so I took the scanner off the Yagi and used the body block technique with the rubber duck antenna, off some and on some, and used the attenuator built into the scanner. Using this technique to find the null and a general direction we knew we were getting closer. Most of the hounds were struggling a bit so the fox gave one hint and we were within a few hundred yards at that time and closing in. I think we would have found him without the hint before much longer but it did let us know we were in the vicinity. My wife and I both enjoyed the experience and look forward to the next one. MSRDF Fox Hunt March 13, 2021 After the fun experience of the February T hunt, we were excited and nervous to try a hunt with a mobile Fox. With the Fox on the move, as soon as he released the Hounds to start hunting, we were a bit surprised when everyone almost immediately engaged the chase leaving us alone in the starting area. Being a ‘lowest mileage wins’ event, our strategy was to move only when we were confident of a good bearing and if possible, drive the bearing instead of triangulating. As we started the hunt and moved closer to the Fox into a more populated area, we noticed folks giving us strange looks as we stood up thru the open roof swinging around in circles. The only way to get more attention would be if we were wearing tin foil hats. At the one hour mark and our 4th stop we were confident we had either come down a dead end path or we were right on top of the Fox. Luckily for us, 100 yards away around the next curve we found the Fox. As we waited for the other competitors to arrive and see who had the lowest mileage, we relaxed and enjoyed the Fox taunting the Hounds. It was good to meet folks and be able to put faces with callsigns and names. We had a great time on our first fox hunt and plan on attending more events. The MSRDF Fox Hunt on March 13, 2021 I recently had the opportunity to participate in my first fox hunt. I have been a licensed amateur radio operator for less than a year and have been having a series of "firsts" and this is another one. Due to the events of 2020 there haven't been many in person events to participate in as a new radio operator. As things are settling down a bit in 2021 a Fox Hunt was a great way to do an event but stay socially distanced. The fox was off and transmitting a very strong signal. My yagi worked great and I was able to identify the direction the signal was coming from using two different locations. Unfortunately my map and general direction sense were not up to par with my yagi's performance. The bearing lines I drew on my map to begin my triangulation sent me astray. Several stops and readings later I was able to work myself back close. Unfortunately the fox's signal was still very strong and my offset attenuator was not up to the task. This led to a bit of wandering, but I was eventually able to stumble upon the fox. While my performance was not what I expected, I learned a lot from this experience and most importantly had a lot of fun with my family along for the ride. I will have a compass, better map, and probably a phone app or two to help my triangulation skills the next time around. I am already looking forward to it. - Kyle Conway, KI5JCL My Expereicne in the MSRDF Fox Hunt March 13, 2021 Don Loper, N5SPJ The day’s hunt began with the sign in and logging of mileage on Saturday morning by 9:15 am. The process began much earlier in the week for the day’s hunt. I was definitely not as prepared as I should have been, but we arrived with not a lot of extra time to spare and got signed in and received our instructions for the hunt. I chose a myriad of antennas I had on hand, none of them being a 2M antenna. The antennas I took with me were in the 700 – 800 MHz range. They were Yagi’s so I would obtain the directivity, but with them being well out of the operation range we were hunting for helped to attenuate the signal since I did not have an attenuator of any type. My arsenal included an SDR dongle and a couple of handhelds. I had one handheld attached to a magnetic antenna on the top of the car, and I started playing with the different antennas which included a military surplus antenna marked “Confidential” that was supposed to be highly directional. After trying a couple of the antennas, I settled on one that gave me a relatively decent signal and had good directionality. Not knowing how well my equipment all worked together and not having tested the antennas with it could have worked against me more than it did, however we headed off in the first general direction after the “Hounds” were released. Trying to keep our mileage down we went in a general direction, took another reading and headed off again, only to find that this direction was misleading. We backtracked and got back on the correct general path to the Fox. As we got close the Fox had to relocate because of several vehicles parking near him and obscuring his location even more. I believe that we were getting several readings that were mis-leading because it appeared the signal was bouncing. I switched to my handheld later in the hunt and continued homing in on the Fox with it. One thing I would have liked to have had was a radio or receiver with an analog meter. The digital ones indicate a change by lighting multiple segments at a time to indicate a rise or turning off a group of segments at a time indicating a fall in the signal, the analog meter would have given a more gradual change making it easier to see the changes. The last time I had to locate a transmitter, it was for my work and I utilized my service monitor as the receiver and it has an analog meter on it making it much easier to see changes in the signal levels. By this time our Fox (K1REZ) had become sleepy and his transmissions were farther apart. Actually, the first finders had arrived and distracted him. We made one more reading and headed in his direction making us the last to arrive. But fear not, even though we were the last to arrive, after the mileage was tallied we were actually in third place. When planning to participate in one of these events, find a known transmitter, this could be a friend’s station, a National Weather Service transmitter, ATIS system at the airport or other known source with continuous or frequent transmissions. Take your equipment and make several tests and see how your equipment interacts with each other and how well the directionality of your antenna is. Move to several different locations and take readings and check that against your known location of the transmitter you are testing with. All of these things will help hone your hunting skills and help you to know your equipment and how all the pieces interact with each other better. One last thing is a good map or mapping system to plot your readings onto. This would have helped immensely had we had one covering the area with us. - Don Loper, N5SPJ |
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