In spite of the usual things we do to reduce and eliminate local noise, we still find ourselves plagued with having to deal with high noise floors, noise induced by local sources, and just having a hard time being able to make out what someone is saying! Aside from the digital noise reduction (DNR) tools that have quickly become rather standard in todays HF receivers, especially SDRs, there are three tools that have proven time and time again to be the most effective in enabling me to pull those hard to hear voices out of the dirt.
The first one is the JPS ANC-4 (now the Timewave ANC+) Antenna Noise Canceller. Here is a brief description of what this does taken from Timewave's ANC+ User Manual:
"The ANC-4+ is an rf device which is designed to provide cancellation of locally
generated noise from signals received by a primary antenna. This unit is employed
right at the antenna connector of the receiver or transceiver to cancel locally gener-
ated noise, such as power line noise, computer noise, TV-generated interference,
etc., before it gets into the receiver and affects the receiver AGC circuits. This
will allow the reception of signals well below the noise level induced by the local
interference."
The second tool is the MFJ-616 Speech Intelligibility Enhancer. This tool is basically a four band EQ that allows you to enhance and contour the frequencies in the vocal range (300Hz, 600 Hz, 1200 Hz, and 2400 Hz) that our ears are most sensitive to. What makes this stand out from other EQ's is the high "Q" of the filters used, and the steepness of the slopes of the EQ curves (I'm guessing they're on the order of 24 dB/Octave), allowing for more aggressive adjustments.
I have fairly bad hearing from years of too loud stereos, I can no longer hear much over 6-7 kHz. (If I jingle my keys, I can barely hear them!) I can listen to music without really missing anything as I can still hear all the fundamentals well enough. However, hearing people during normal conversation can be a problem, especially if the ambient noise level is higher than normal. I can hear them speaking, I just can't make out what they're saying! This has proven to be more of a problem when listening to voices on the radio. Unless they're loud and clear, I miss parts of what they say. The higher the background noise, the less I can make out what they say.
The MFJ-616, with its aggressive tone controls, has done more to enable me to hear what people say than any other noise reduction tool I have ever used. Such that, if I were stranded on a desert island with only a basic radio, and the choice to bring only one noise reduction tool, the MFJ-616 would be my first choice!
Finally, the third tool is the RF Gain control. Before doing anything else, I'll first tune to the band I want to listen to, tuning to where there are no signals. With the RF Gain set to maximum signal, I will then get the S-Meter "bouncing" at mid-point, turning on a preamp or attenuator if needed to do so. Then, I adjust the ANC-4 to get the lowest S-Meter reading I possibly can. If the indicator gets too low, I just turn off an attenuator, or turn on another preamp, and continue adjusting until the indicator bottoms out. I will then try to get the S-Meter to settle at below 1 S-Unit, with a slight bounce, using the preamp(s), and the attenuators built into the receiver. Doing all of this ensures that I have the best baseline S/N to work from. Unless the best baseline S/N is properly established, you won't get the maximum benefit out of all of your other noise reduction tools and methods!
After that, I will then tune to the frequency I wish to monitor, and proceed to use the RF Gain control to minimize the noise, while maximizing the signal. Then, if it's still too noisy, I'll turn on the digital noise filter, and set that to where the noise is further reduced. Then, I'll adjust the RF Gain a bit more to further reduce whatever noise artifacts are left over from the DNR without degrading the signal. (It can be a fine line to ride!) After all that has been accomplished, I will then use the MFJ-616 to fine tune the resulting sound.
A word about DNR settings. I've found that the FT-710's DNR is smooth up to level 7. After that, it gets more agggressive to where you get that "underwater" sound. However, I've also come to realize that if you let the DNR do its thing at these more aggressive settings, it will quickly differentiate the noise from the signal, and will begin to make the signal more and more intelligible! When it's really noisy, I love setting the DNR to its highest level, and listen to it suddenly bring out the voice so it's very clear against all the noise and warbeling! I've learned to not judge the DNR setting immediately after turning to it. It needs to settle down a bit, before you can accurately determine whether or not the setting will be enough!
There you have it. The ANC-4 is very effective at reducing locally induced RF noise, especially impulse noise. The RF Gain control enables you to further reduce RF noise, as well as artifacts left by DNR. And, finally, the MFJ-616 is really effective at lifting voices out of the noise, and fine tuning them so they're more understandable.
The ANC-4 controls what signals are coming into the radio, the RF Gain control helps you to further control that signal while it's still inside the radio, and the MFJ-616 helps you control that signal as it comes out of the radio!
While the ANC-4 and the MFJ-616 may be expensive, to me they're worth their weight in gold! On the other hand, the RF Gain control doesn't cost a thing, and is also very effective at increasing the S/N, even if you have no other tools you can use! I've heard of how old Hams used to turn the RF Gain all the way down, turn the volume all the way up, and then use the RF Gain control as their volume control!
Hey, whatever works!
Happy DXing!
The first one is the JPS ANC-4 (now the Timewave ANC+) Antenna Noise Canceller. Here is a brief description of what this does taken from Timewave's ANC+ User Manual:
"The ANC-4+ is an rf device which is designed to provide cancellation of locally
generated noise from signals received by a primary antenna. This unit is employed
right at the antenna connector of the receiver or transceiver to cancel locally gener-
ated noise, such as power line noise, computer noise, TV-generated interference,
etc., before it gets into the receiver and affects the receiver AGC circuits. This
will allow the reception of signals well below the noise level induced by the local
interference."
The second tool is the MFJ-616 Speech Intelligibility Enhancer. This tool is basically a four band EQ that allows you to enhance and contour the frequencies in the vocal range (300Hz, 600 Hz, 1200 Hz, and 2400 Hz) that our ears are most sensitive to. What makes this stand out from other EQ's is the high "Q" of the filters used, and the steepness of the slopes of the EQ curves (I'm guessing they're on the order of 24 dB/Octave), allowing for more aggressive adjustments.
I have fairly bad hearing from years of too loud stereos, I can no longer hear much over 6-7 kHz. (If I jingle my keys, I can barely hear them!) I can listen to music without really missing anything as I can still hear all the fundamentals well enough. However, hearing people during normal conversation can be a problem, especially if the ambient noise level is higher than normal. I can hear them speaking, I just can't make out what they're saying! This has proven to be more of a problem when listening to voices on the radio. Unless they're loud and clear, I miss parts of what they say. The higher the background noise, the less I can make out what they say.
The MFJ-616, with its aggressive tone controls, has done more to enable me to hear what people say than any other noise reduction tool I have ever used. Such that, if I were stranded on a desert island with only a basic radio, and the choice to bring only one noise reduction tool, the MFJ-616 would be my first choice!
Finally, the third tool is the RF Gain control. Before doing anything else, I'll first tune to the band I want to listen to, tuning to where there are no signals. With the RF Gain set to maximum signal, I will then get the S-Meter "bouncing" at mid-point, turning on a preamp or attenuator if needed to do so. Then, I adjust the ANC-4 to get the lowest S-Meter reading I possibly can. If the indicator gets too low, I just turn off an attenuator, or turn on another preamp, and continue adjusting until the indicator bottoms out. I will then try to get the S-Meter to settle at below 1 S-Unit, with a slight bounce, using the preamp(s), and the attenuators built into the receiver. Doing all of this ensures that I have the best baseline S/N to work from. Unless the best baseline S/N is properly established, you won't get the maximum benefit out of all of your other noise reduction tools and methods!
After that, I will then tune to the frequency I wish to monitor, and proceed to use the RF Gain control to minimize the noise, while maximizing the signal. Then, if it's still too noisy, I'll turn on the digital noise filter, and set that to where the noise is further reduced. Then, I'll adjust the RF Gain a bit more to further reduce whatever noise artifacts are left over from the DNR without degrading the signal. (It can be a fine line to ride!) After all that has been accomplished, I will then use the MFJ-616 to fine tune the resulting sound.
A word about DNR settings. I've found that the FT-710's DNR is smooth up to level 7. After that, it gets more agggressive to where you get that "underwater" sound. However, I've also come to realize that if you let the DNR do its thing at these more aggressive settings, it will quickly differentiate the noise from the signal, and will begin to make the signal more and more intelligible! When it's really noisy, I love setting the DNR to its highest level, and listen to it suddenly bring out the voice so it's very clear against all the noise and warbeling! I've learned to not judge the DNR setting immediately after turning to it. It needs to settle down a bit, before you can accurately determine whether or not the setting will be enough!
There you have it. The ANC-4 is very effective at reducing locally induced RF noise, especially impulse noise. The RF Gain control enables you to further reduce RF noise, as well as artifacts left by DNR. And, finally, the MFJ-616 is really effective at lifting voices out of the noise, and fine tuning them so they're more understandable.
The ANC-4 controls what signals are coming into the radio, the RF Gain control helps you to further control that signal while it's still inside the radio, and the MFJ-616 helps you control that signal as it comes out of the radio!
While the ANC-4 and the MFJ-616 may be expensive, to me they're worth their weight in gold! On the other hand, the RF Gain control doesn't cost a thing, and is also very effective at increasing the S/N, even if you have no other tools you can use! I've heard of how old Hams used to turn the RF Gain all the way down, turn the volume all the way up, and then use the RF Gain control as their volume control!
Hey, whatever works!
Happy DXing!
