Analyzer Setup

By Larry Wassman W3OZ

How to use Spectrum Analyzers like HamAlyzer

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This is a typical display (fig 1. ) using the HamAlyzer spectrum analyzer software package. The ham who I captured here was 59+10 or so, at my station, so I had no problems copying him. I did 2 scans on him and they were both almost the same as the one shown here. I know this ham's normal voice and I would describe the audio he was projecting as being kind of robotic and nasal. I am not saying that everyone wants to sound like CBS or NBC, but unless you are trying to cut through a DX pileup, this audio is kind of hard to listen to for a long time. Look at the display below and observe where most of his energy starts and where it ends. Freq 1(his bottom end) is 355Hz and Freq 2 (his high end) is 2368Hz. or an effective bandpass of 2013Hz. His radio is set up correctly, and he is using a standard microphone that came with the rig he is using. What could he do to make his audio better after looking at this chart?

fig 1

The radio he is using is a newer model DSP type radio with all the bells and whistles. It has plenty of menu selections to make him sound better. He has selected a very narrow filter which is fine for DX work, but is this appropriate for talking to your buddies when you are 59+ coast to coast? Smooth pleasant sounding audio is balanced and should use most of the spectrum that your radio is capable of passing. This particular radio has the ability to pass 3000Hz, but the ham is only using 2013Hz. What about the remaining 987Hz? What about the spikes and valleys in this signal? Wouldn't it sound better if they were smoothed out? Look at the big spike at about 2200Hz? In general, the chart should start at a point on the left and have a very slight slope to the right without any big spikes or valleys. A lot of energy at the high end makes for a tinny sound, if there is no balance on the low end. An over abundance of bottom end energy can also make for a booming sound that is just as bad. Key word balance.

fig. 2

Here is a graph (fig. 2) done on a ham who is using an ICOM 775 with outboard audio processing equipment. As you can see, almost all bandpass of this radio is being utilized. His bottom end is at about 96Hz and his top end is at approximately 3000Hz plus or minus a little. Now this is pretty good in that the radio is not supposed to go beyond 2.9Hz on the top end. The little extra is called EQ push. To make the sound better in my mind, he could bring the top end down a little so that the slope was in there, but this is typically what you can do with the proper settings and equipment. Believe me this ham has spend a lot of time speaking into his dummy load while doing many graphs of his audio. He is proud of it and he should be so. There are some little peaks and valleys, but noting to extreme. You could listen to him all night and it would be as though he was setting in your living room or you were listening to him on a commercial radio station. Would you want to listen to a commercial radio station that sounded like the ham in fig. 1? I don't think so.

fig. 3

This picture, fig. 3 shows another way of using a spectrum analyzer package to compare different signals using the "Overlay" feature that is part of most analyzer software packages and especially part of HamAlyzer. Here you can see a HI FI Audio signal compared to a typical signal. The HI FI signal is in light blue and the normal signal is in green. You can easily see how much useful information could be added to the signal if the ham expressed in the green chart just added a little to his setup to improve the quality of his audio. In fact during the time I was taking the snapshot of his audio he was bragging about how good he sounded. I am not making fun of this person, but simply trying to illustrate what could be done by adjusting your audio and how a good spectrum analyzer program can make it easier to see how you are doing.

First you have to know what your audio signal sounds like, by monitoring yourself as you speak through the monitor in your rig. Use a good set of headphones when doing this. Turn up the volume to where it is a little uncomfortable and listen. Do you like what you hear? Does it sound like what you want to sound like? Is there sufficient lows and highs? Remember you are the only one who matters. Is there a lot of extra noise coming on the air with you, like fans, computers, or sounds from other parts of your home? If you hear anything you are not proud of, you can work to put out an audio presentation to your fellow hams that you will like.

Hooking up your radio to a computer sound card is not that hard and can be as easy as getting a cable at Radio Shack. Be sure you know what size and type of plugs you are working with. Most sound cards use 1/8 plugs. Some radios also use 1/8 plugs, but you may have to take the audio out of DIN plug, so check before you go to get the cable. You can take the audio from the fixed output on the back of most radios or even take it out of the speaker jack. You could also do it a little cleaner as I describe on this page in setting up to record. Click here to go to that description and discussion. By the way if you come out of the speaker jack, be sure not to overload the line input of your sound card. It is not a fixed low level output and if the volume is up to high you will have problems. You will probably not do any real damage, but you will get a distorted reading of your audio. Don't use the mic input of the sound card unless that is the only port you have on the card. Most sound cards have both line and mic inputs.

Get and install a Spectral Analysis software program like the one I am using by the name of HamAlyzer. Click HERE to go to the web page and at least get the demo copy which has all the functions turned on for a 10 day FREE trial. I have no financial interest in this software or it's author. I simple believe it is the best software for all hams interested in good audio, unless you are a pro audio engineer with a lot of money. If you are one of those individuals, then maybe one of the other packages available that I mention on other parts of this page, will be for you.

Even if you do not get the Analyzer software and monitor your signal that way, you can make improvements by doing and getting just a few things. Set up your radio correctly. Go to other parts of this page to see how to do that. If your rig has setup menus, know about them and use them. Get a better microphone that will pass all the frequency that your rig is capable of passing. You would think that the mic that came with your rig would do that, but they don't always. Some hams are using the old mic that they got at a flea market 30 years ago on a $3,000 new DSP rig. Not a good idea. Look at reducing the ambient noise in your shack. Maybe get an outboard noise gate. Make sure your mic gain is set correctly and if you use processing, make sure it is setup correctly? Many hams use the compressors in their rigs to project more audio, but this may not be the best way to do it under rag chew conditions. Maybe for DXing when the conditions are different, but you would not want to listen to someone that sounds like that for very long.

There are many, many ways to make the above chart look better with external audio gear. I cover all that stuff in other parts of this page. Go back to the "Audio Setup" pages and check it out. It is not really that expensive or difficult. By using outboard audio gear like equalizers (EQ), noise gates, compressors, and special effects boxes (FX), you can use Spectrum Analyzers to expand the range of your audio and take some of the peaks and valleys out of your signal as was shown in the above fig 1. In that example, you would look at the chart and boost, or cut the frequencies as indicated. On a graphic equalizer, one with sliders like most home HI FI equipment, you would move the corresponding slider up or down until the chart was smoothed out. On a parametric equalizer you would adjust the frequency, bandwidth, and gain. You could then apply some FX (effects) like some reverb, and polish your audio signal. Of course this is all up to your own personal goals and you do not have to have any of these boxes to sound better. As I said before, I could make most rigs sound just great and have a nice smooth chart with very few dips and spikes with all the bandwidth that my rig could provide for between $200 and $300.

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