Three steps to getting rovers on Linear sats

First off I do not know what I’m doing when it comes to chasing the rovers on linear sats. I seem to get lucky more often than not. But some of my buds on Twitter have asked me for how I do it, so I thought I would write something up…. So when you evaluate the information in the article, please remember how much you paid for it.

 

From what I can see there are three phases to chasing rovers on the linears: Starting from the simple to the advanced those phases are: Finding yourself, moving through the pass band and finding the rover for the qso. I will cover how I learned and use all three of these methods.

 

This article will assume a few things: You have a full duplex set up, and a basic knowledge of how the set up your radios for communicating through the linear sats. This is mostly for people with a 1634, but the same methods can be used with a 910H or 9700.

 

Step 1: Finding yourself.

We will start off by using my frequency cheat sheet available here: Cheat Sheet. If you’re not familiar with how to use the sheet, please read that article. Now that you have the sheet and know how to use it, let’s go talk to ourselves. Fire up your sat tracking application and radios. For this example, we will use CAS-4B, and here are the frequencies for that sat.

Set up your radios for the middle of the passband, at AOS: 145.925, and 435.270. When the satellite is in view, start calling CQ, (don’t wait to be at 20 degrees, start right away)  and slowly raise your UHF frequency until you hear yourself. We know that the frequency won’t be below 435.270, and most likely will not be higher than 435.275 at AOS, so you should find yourself fairly easy. If you miss yourself, don’t be afraid to move back to 435.270 and start over.

Couple key points:

• • If you miss yourself, don’t forget to rotate the arrow for polarity.
  • Don’t move your VHF frequency.
  • You will make QSOs starting in the middle of the passband, that is where most people start the pass, and they will hear you, and call you.
  • Once you get good at finding yourself, move away from starting in the middle of the passband. You can use this sheet and process to start anywhere in the passband

 

Moving through the passband:

Some people have trouble losing themselves when moving through the passband. I have a couple tricks I use to make it easier to do this, and still find myself. All this is again, based on my Frequency Cheat Sheet, and a simple fact: If you move up 3 on VHF, you need to move down the same on UHF and vice versa.

If other words If I start at 145.930 and find myself and then move to 145.920, I lowered my VHF by 10, so I need to raise my UHF by 10.  Even if you’re not exact, using this method you will be close and be able to hear yourself and fine tune to make that qso.

Another method is using the frequency sheet. If my VHF is at 145.920, and I can’t hear myself, I look at my sat tracking app, and if the pass if about 40% way through, I look at the cheat sheet and see that 435.280 (not AOS but the next one down) is where the UHF needs to be. I always choose the lower frequency so that I know that I need to raise the UHF to find myself. Again, not going to be perfect, but it’s close enough to hear yourself.

Key Points:

• • Move through the passband using VHF, then only tune the UHF to hear yourself
  • If you use the Cheat Sheet method to find yourself. You almost always have to raise the UHF frequency to find yourself.

 

Finding the Rover:

This is where we put the steps together. Usually the rovers will announce where they will be. +5 from the center for example.

For some reason I can usually hear chatter on the sat before I can hear myself. I use this brief time to see if I can find the rover. Let’s assume that AD0DX is lighting up another rare grid, and he is at 5 from the bottom on 4B – 145.920. I usually go to that frequency and see if he is there calling CQ. If he is, I do some quick math, so I can go to a quite spot on the passband, find myself and then move back for the qso. Using this method, I’m not taking up the rover’s time while I find myself, and I’m not speaking over other people trying to get that contact.

OK, back to the steps:

1. 1. Find Ron. Turns out I heard him call at 145.932, not where I thought he would be.
   2. I figure that if I subtract 10, that should be a quite spot, so I scoot to 145.922, and find myself.
   3. Using the chart this should not take very long. I find myself, then…
   4. Add 10 to the VHF, and subtract t 10 on the UHF and…
   5. There he is. As soon as possible I call him. Since I should be pretty close, he should be able to make me out, and I should be able to hear him.
   6. Get the QSO, the grid and a big smile.

Key Points:

• • Practice this.
  • If you don’t get the qso right away, go back to a clear spot on the passband and check to make sure you can still hear yourself. Protect the rovers time. There are others trying to get the grid.
  • Use easy math increments. 5 or 10 Khtz. Make the math easy.

Ok, these steps make it sound pretty easy, and at the beginning it wasn’t. I spent a lot of time practicing this before I got it down.

What I’m saying here is the steps are simple, but you still need to practice this. Don’t think you are going to read this article, print out the Cheat Sheet, and then go get DL88 in a big pile up. You need to work on this.

 

Thanks for reading this and if you have any questions, please feel free to hit me up. @ke0pbr on Twitter.

 

If you want to hear an example of the finding the Rover, here I contact KI7UXT for a grid:

Here is a link to the recording: Recording of CAS4B

K7U announced that they would be +5 or -5 from center. On Cas4B center is 145.925 so I figured I would go for -5 at 145.920. So I decided I would find myself at .915 and then move to .920

On the recording you will hear me finding the sat from 0-36 seconds, during this time I also learned that someone else was at .915. So I changed plans to go for the rover at +5 and find myself at .935. At 0:36 you hear me finding myself. Once I found myself, I subtracted 5 from UFH, and Added 5 to VHF, and I knew I would be close to one of the guys. At 0:46 you will hear me finding KI7UXT and making a QSO. After that I just jumped around and made a few other QSOs,

 

My Frequency Cheat Sheet

Updated 9/11/21

A few people have asked for my frequency cheat sheet for the linear sats. So I just decided to post it here for everyone.  Here is the download =>ke0pbr-freq-cheat-sheet 12-14-22 (12/14/22 I added CAS-5)

I use this to quickly “find myself” on the linear sats. How I do this is fairly simple, at least in my simple mind.

Here is an example using FO-29, with full duplex, but I think this process could work for simplex ops too.

Each sat has 6 rows, the first 5 are for UHF Doppler adjustments, the last is for VHF:

1. AOS
2. 1/2 way between AOS and mid pass
3. Mid Pass (No Doppler (also green)
4. 1/2 way between LOS and Mid Pass
5. LOS
6. The last row is the 2 Meter non Doppler adjusted frequency (Also Green)

Each satellite, also has columns that range the entire passband, so this can be used across the full spectrum of frequencies.

When I loose myself, I see how far into the pass I am. For this example I will assume the satellite is just past mid pass or a little over halfway done.

I first adjust my VHF to one the closest VHF frequency (lowest green bar) lets say 145.960. Then since the sat is just past mid, I set the UHF at the frequency for mid pass, in this case 435.840. Since we are past mid, I know that I must adjust the UHF frequency lower, because that’s the next line down on the cheat sheet. as I move the frequency down, I know I will hear myself shortly.

One thing to remember, the sats with a red bar on the left of the frequencies Doppler goes down, if there is no red bar, Doppler correction goes up.

If you have any questions, please feel free to ask!

KE0PBR

 

Excel Version:ke0pbr-freq-cheat-sheet 12-14-22

PDF Version: Freq Cheat Sheet 12-31-21