Test Equipment Requirements
What test equipment is recommended to monitor and maintain a radio station?
It often happens that we receive phone calls from people that manage radio station concerning problems; unfortunately, most of them do not have the necessary equipment to verify where the problem could be. This is a brief explanation and list of the type of equipment every Radio station manager or technician should have on hand. In my experience, most people care about the the programs and music they are broadcasting but do not pay much attention to the quality of the sound and the right way to monitor it.
1) RF OUTPUT POWER
Every FM radio transmitter has a display that shows the actual output power of the unit in Watts; the FCC requires that the output power has to be kept at a pre determined level. The meter that displays the power on the transmitter is not very accurate (every brand) and you cannot totally trust what you read because the reading is changing depending on the operating power and frequency. Having an accurate reading system in the transmitter would mean to lightly increase the cost of the unit. For this reason we recommend the use of an external wattmeter to insert in the feed line; this will give you a much more accurate reading of your output power. The most common wattmeter insertion (universally used) is the Bird 43 model that you can buy new or in many cases also refurbished. With the use of the proper slug inserted you can read forward power and reflected power so that you can also monitor the status of your antenna system. The accuracy of this test equipment is about plus-minus 5%. Available slugs have a specific frequency range and full scale indication reading. In our Ebay store you can often find refurbished units at a reasonable price. The slugs that go inside the unit are normally sold NEW and you can buy them through us or throu a Bird distributor.
2) MODULATION CONTROL
Our transmitter have a very nice sound, but they must be installed in the right way and fed with the right amount of audio level. The use of an audio processor device is almost mandatory to keep the level of the sound constant. We have a choice of analog and digital audio processors that can help you in doing that. When you broadcast in mono a good audio processor with a proper setting can do the job; when you deal with stereo modulation you have more issues to take care. May be not many of you know that the stereo emission is generated by a subcarrier signal generated by a stereo coder. This subcarrier signal is set at 19 Khz distance from the main carrier and his amplitude has to be set at a specific level. If you have a Spectrum Analyzer (very useful equipment) you can easily see the subcarriers when you don't have modulation and you can regulate the level to -14dBm from the main carrier. This is the proper setting and when you have more than one frequency you should set all of your frequencies at that level. Unfortunately a Spectrum Analyzer is quite expensive; we have sometimes some available in our Ebay store. If you don't have one or you cannot afford to buy one, you still need to find a way to control this level. In this case we recommend the use of a Modulation Monitor that, besides other features, performs also the reading of the subcarrier levels. And furthermore you can control the subcarrier also when your radio station is operating with the modulation so you don't need to interrupt the emission to make this adjustment. But why is so important to keep the subcarrier level at this level? Because this level is internationally set for broadcasting stereo and because when you have set all your frequencies with the same subcarrier level your volume of sound will be exactly the same in all your frequencies and when you regulate the audio processor from the studio, all of your frequencies will be regulated in the same exact way. Our MM2007 Modulation monitor performs this feature and other like the control of left and right channel, the reading of the separation between channels etc. Furthermore it has a built in programmable receiver so that you can monitor not only your radio station, but also other radio stations like your competitor's one and see if they perform well or not. Our modulation monitor has also a built in decoder so the composite radio signal received can be decoded in left and right channel.
3) CONCLUSION
There are many more testing equipment that we have in our lab and that could be very useful (distortion analyzer, network analyzer etc.)but we understand that in most cases is not possible to handle the cost of all these equipment. For this reason we just indicate those that we consider of primary importance for a proper performance of your emission. Our technicians will be happy to answer any question you may have; you can email at any time at info@nicomusa.com
It often happens that we receive phone calls from people that manage radio station concerning problems; unfortunately, most of them do not have the necessary equipment to verify where the problem could be. This is a brief explanation and list of the type of equipment every Radio station manager or technician should have on hand. In my experience, most people care about the the programs and music they are broadcasting but do not pay much attention to the quality of the sound and the right way to monitor it.
1) RF OUTPUT POWER
Every FM radio transmitter has a display that shows the actual output power of the unit in Watts; the FCC requires that the output power has to be kept at a pre determined level. The meter that displays the power on the transmitter is not very accurate (every brand) and you cannot totally trust what you read because the reading is changing depending on the operating power and frequency. Having an accurate reading system in the transmitter would mean to lightly increase the cost of the unit. For this reason we recommend the use of an external wattmeter to insert in the feed line; this will give you a much more accurate reading of your output power. The most common wattmeter insertion (universally used) is the Bird 43 model that you can buy new or in many cases also refurbished. With the use of the proper slug inserted you can read forward power and reflected power so that you can also monitor the status of your antenna system. The accuracy of this test equipment is about plus-minus 5%. Available slugs have a specific frequency range and full scale indication reading. In our Ebay store you can often find refurbished units at a reasonable price. The slugs that go inside the unit are normally sold NEW and you can buy them through us or throu a Bird distributor.
2) MODULATION CONTROL
Our transmitter have a very nice sound, but they must be installed in the right way and fed with the right amount of audio level. The use of an audio processor device is almost mandatory to keep the level of the sound constant. We have a choice of analog and digital audio processors that can help you in doing that. When you broadcast in mono a good audio processor with a proper setting can do the job; when you deal with stereo modulation you have more issues to take care. May be not many of you know that the stereo emission is generated by a subcarrier signal generated by a stereo coder. This subcarrier signal is set at 19 Khz distance from the main carrier and his amplitude has to be set at a specific level. If you have a Spectrum Analyzer (very useful equipment) you can easily see the subcarriers when you don't have modulation and you can regulate the level to -14dBm from the main carrier. This is the proper setting and when you have more than one frequency you should set all of your frequencies at that level. Unfortunately a Spectrum Analyzer is quite expensive; we have sometimes some available in our Ebay store. If you don't have one or you cannot afford to buy one, you still need to find a way to control this level. In this case we recommend the use of a Modulation Monitor that, besides other features, performs also the reading of the subcarrier levels. And furthermore you can control the subcarrier also when your radio station is operating with the modulation so you don't need to interrupt the emission to make this adjustment. But why is so important to keep the subcarrier level at this level? Because this level is internationally set for broadcasting stereo and because when you have set all your frequencies with the same subcarrier level your volume of sound will be exactly the same in all your frequencies and when you regulate the audio processor from the studio, all of your frequencies will be regulated in the same exact way. Our MM2007 Modulation monitor performs this feature and other like the control of left and right channel, the reading of the separation between channels etc. Furthermore it has a built in programmable receiver so that you can monitor not only your radio station, but also other radio stations like your competitor's one and see if they perform well or not. Our modulation monitor has also a built in decoder so the composite radio signal received can be decoded in left and right channel.
3) CONCLUSION
There are many more testing equipment that we have in our lab and that could be very useful (distortion analyzer, network analyzer etc.)but we understand that in most cases is not possible to handle the cost of all these equipment. For this reason we just indicate those that we consider of primary importance for a proper performance of your emission. Our technicians will be happy to answer any question you may have; you can email at any time at info@nicomusa.com
