Re: More progress in using SDRSharp, for those interested
Even though I'm still really new to using SDR, I'll try and write down some ideas on how I'd approach it. Also note that there are two things you need to get started, a receiver and the software for controlling it.toggle quoted messageShow quoted text
There are a number of receivers that are available, starting out at around twenty dollars up into the hundreds for some of the really high end ones. The second part, the software is where things get a little tricky. In as far as I've been able to figure out, the two best options for Windows are SDRSharp and HDSDR. I wont really go into detail on the differences between the two, as I don't want to bore anyone with stuff I've already mentioned previously on list, but if it's of any interest, certainly feel free to let me know and I'll describe things more with the both of them. Basically though, with SDRSharp and the keystrokes autohotkey application I mentioned before, this is how I would go about listening to the bands as things work currently.
Once you get the drivers for the receiver you want to use installed, you'd also make sure to have the SDRSharp and shortcut keys applications saved to a folder. While it's not necessary to have the shortcut keys running to test the receiver, change some of the options like volume, press the play button etc, you will need it to change other areas that aren't reachable by the screenreader by pressing tab.
Once SDRSharp is running for the first time, you can tab to the section where you select a source, so you'd select your receiver with the up or down arrow keys. Once your receiver is selected here, you can tab quite a bit until you reach a section that contains three buttons in a row. The first button you come to in these three buttons is the play button. Before you press play for the first time, I would recommend tabbing a bit more until you reach a slider, which is the volume. When you first download SDRSharp and run it, the volume here tends to be set quite high, so if you press play and it's set to something like NFM, you might get quite the shock to your ear holes when the unsquelched noise comes blaring through your headset. I'd set this slider to around 20 or so and then shift tab back to the play button and press space. You should then be able to hear sound.
It's at this point that it might be useful to launch the shortcut keys application, and also read through the accompanying notes to get an idea of how the keyboard shortcuts are currently configured. You can also open up the .ahk file that Dale sent with the executable with notepad and read the actual script, but the notes are easier to read at the start. The difference between the executable and the text version of the script is the text script requires that you run it with the autohotkey application, whereas the executable version is everything all in one package so it's easier to use that one.
Once you run the shortcut application, you will notice that your system volume will drop down to around 30 percent. The script is set to do this automatically, so you can use your volume slider in the system tray or the shortcut key he added in the script to raise it back up, control+up arrow. You'll notice in the notes that most of the other keys are simple one letter shortcuts, so as my example here, f for moving to the frequency area field where you can type in the frequency.
I'm not sure what screenreader you're using, but with NVDA, pressing f in the SDRSharp window says unknown. This basically means that NVDA isn't able to read what's actually here, but you can still use your number keys to enter a freq or your left, right, up and down arrows to move around in the field. Every time you press f, it jumps you to the same position in the field, so in the hundred megahertz part. The notes also explain this and how to go about entering a frequency, but I'll try and explain it here too.
When you enter a frequency with the numbers, it automatically fills in the remaining zeros to the right. This means that you don't have to type in a massivly long number, so if you wanted to jump to 460 megahertz, you'd type f, 460 and then enter. You could also type f, 46 and enter, as it should add the 0 to the right of the 6, but it's habit to add the 0 for me. Keep in mind that the entire frequency field is 12 numbers long, from left to right, with the very left number being the hundred gigahertz, ten gigahertz, one gigahertz, hundred megahertz, ten megahertz, one megahertz, etc. This means that the number to the very right of the field is the one hertz position. Once you enter your frequency, you can use your right arrow to move to the number you want to change, so ten kilohertz and use the up and down arrow to move it up and down on the fly. If you've pressed the play button and you have sound, you can hear it as you move through the band by that amount. It will also depend on what stepsize you have selected as to how much your movements through the band actually move you, so this is where being able to see the current frequency in that area would be better. For now though, I just try to keep track of it in my head how much it will move me by my stepsize and by how much it should move me depending on how I am moving up and down through the band, so by tens of kilohertz or whatever.
When you're listening to VHF and UHF it will be pretty important to set your squelch, so when you select NFM as the modulation, you'll notice that this option becomes available and you can tab to it. the squelch checkbox should be selected by default, so pressing tab once more takes you to a combo box where you can adjust it. NVDA mislabels this combo box and reads it as CW shift rather than the level of squelch, so keep that in mind that some of the stuff reads kind of weird. You could then either look up local frequencies and enter them as described or you can jump roughly to the area in the frequency spectrum you are interested in and move through it in smaller steps until you hear a broadcast. For stations that are constantly transmitting, such as radio stations, the weather station etc, moving through the band is much easier, but it does work for the ones that don't.
As soon as we get back in a bit, I'll also post up the files I've been using to dropbox, but that should be enough info to hopefully give an idea on how to get started.
On 4/20/2017 12:43 PM, Jim Wohlgamuth wrote: