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HF/MW/LW General Discussion General discussion on monitoring the HF (High Frequency), MW (Medium Wave), and LW (Long Wave) spectrum (0.5 - 30 MHz)

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Old 07-14-2014, 5:43 PM
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Question Frequncy Format

.
e.g.: 12.345.678

Does this style have a name? and also could someone enlighten to some of its history??
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Old 07-14-2014, 6:54 PM
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The only name that would have is "confusing" (in the US, anyway, some Europeans use decimal points as thousands separators). But in such a case where is the decimal point (radix point) supposed to be? What frequency range does this number fall into?

Assuming that frequency was someplace in the HF spectrum, between 3 and 30 MHz, there could be several ways to report that frequency.

12.345678 MHz would work.

Most forums use frequency in kHz in the HF range, and MHz in the VHF and up range. So that your frequency (again, assuming it is in the HF range) would be 12345.678 kHz. Personally, I like kHz in the HF and down spectrum, it just looks cleaner to me.

And Hz is also possible, in this case it would be 12345678 Hz. However few people really measure down to the Hz on HF, indeed for some signals (such as SSB) it would not be possible unless you have a reference of the audio transmitted, such as a known audio tone.

T!

Last edited by Token; 07-14-2014 at 7:01 PM..
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Old 07-15-2014, 2:32 AM
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I've never seen the need to use frequency readouts further than half a kilohertz. I just don't see the point in it.

Seeing a report of a station on 7345.217 Khz just seems pointless. I'm sure as SDR technology progresses they will be able to carry out the precise reading of the kilohertz to another hundred digits.

And I'm also sure there will be SWL's who will use such readouts in their reports.

"Wow, I just got WWV at 10000.012313337293023949283 khz."

It's only a matter of time.
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Old 07-15-2014, 2:57 AM
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Quote:
Originally Posted by crazy_19 View Post
.
e.g.: 12.345.678

Does this style have a name? and also could someone enlighten to some of its history??
Yeah, it's called an IP address. Radio usually only has one dot.

An example would be 14.160 mhz, my favorite spot on 20 meters to call CQ.
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Old 07-15-2014, 3:35 AM
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Originally Posted by pinballwiz86 View Post
Yeah, it's called an IP address. Radio usually only has one dot.

An example would be 14.160 mhz, my favorite spot on 20 meters to call CQ.
Although you're most likely attempting to be funny, you fall short. IP Addresses (v4 anyway) have 3 dots, not 2. Also the numbers between the dots don't exceed 255.

Many HF radios with digital displays use a period in their display to break up the frequency to make it easier to read. On those 14,250,390 Hz will display as 14.250.390. Kenwood's do it. Icom's do it. Yeasu's do it. If you look closely at the software driving the modern Flex Radios, even they do it.

I believe that the style (in response to the original question) doesn't really have much magic to it, it's simply that the old digital displays could show numbers and periods. To help break up the frequency and make it easier to tell 1425000 from 14250000, they used what they had, periods (or dots, decimals, etc.) so it was easy at a glance to know it was 1.425.000 or 14.250.000.
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Old 07-15-2014, 3:53 AM
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Although you're most likely attempting to be funny, you fall short. IP Addresses (v4 anyway) have 3 dots, not 2. Also the numbers between the dots don't exceed 255.
Tough crowd.
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Old 07-15-2014, 8:35 AM
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I've never seen the need to use frequency readouts further than half a kilohertz. I just don't see the point in it.
Have you ever told someone on HF that they are "off frequency" if the frequency they are using doesn't end in a 5 or 0?

When the bands are crowded sometimes you have to find a spot in between two ongoing contacts, which can sometimes lead to odd frequencies (such as 14.201.75). Also for those of us that are CW ops, those extra Hz steps can be quite useful.
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Old 07-15-2014, 10:12 AM
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Point taken.

But I don't see the reason to place it three or four digits when reporting broadcasters on various DX log forums. I've seen it done in cases it just was unnecessary information. :-)
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Old 07-15-2014, 10:15 AM
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Originally Posted by Boombox View Post
I've never seen the need to use frequency readouts further than half a kilohertz. I just don't see the point in it.

Seeing a report of a station on 7345.217 Khz just seems pointless. I'm sure as SDR technology progresses they will be able to carry out the precise reading of the kilohertz to another hundred digits.

And I'm also sure there will be SWL's who will use such readouts in their reports.

"Wow, I just got WWV at 10000.012313337293023949283 khz."

It's only a matter of time.
I think the OP was asking a general question about the format of the frequency readout, not trying to comment on how many digits a signal should be reported too.

This issue of frequency reporting resolution has many facets.

The first is, regardless of how many digits your frequency display is, how accurate is the calibration of that display or how you are detecting the signals frequency? Just because your display goes to Hz does not mean you are accurate within Hz. Regardless of how accurate your readout was when the receiver was first aligned, unless you have it reference locked it will drift. Yeah, all kinds of things like ovens and such can reduce this, but it will eventually be off by a significant amount. You can also calibrate or normalize on the fly, that is check the frequency readout periodically against a known signal, such as WWV, but still there exist a problem of how to confirm it to the Hz level, typically something like detected audio and an oscilloscope will address that issue. If you do not lock your RX to a reference source or you have not recently confirmed the calibration of your frequency display then reporting to the Hz is a waste of time.

And how are you detecting the signals frequency? If it is an AM station are you simply tuning for a peak? If it is an SSB station are you simply tuning to the best sounding audio to your ear? If it is a CW station are you simply tuning by ear to the CW pitch you like? While all of these are common practices, and perfectly adequate for most listeners, not one of them will yield accuracy down to the Hz, except by random luck. Of course these techniques work well for listening, but not for finding frequency to a very tight standard.

Next is, do you need that kind of resolution? Leaving hams out of the equation here, since this is posted in the Monitoring segment of the forums. For the typical SWL doing BC stations there is probably no need to go finer than maybe 0.1 kHz. An argument could be made even 1 or 5 kHz is adequate, but 0.1 kHz can help ID obscure stations with known transmitter offsets. But what about the Utility listener? Many times Ute stations do not fall on even 1 kHz frequency steps. Some users can be identified by their chosen frequency offset, such as one networks common use of XXXX.6 kHz frequencies. Some digital modes must be tuned within a few 10痴 of Hz at worst, meaning you must get the freq correct to get the decode, and to get the freq correct you must have it reported to you correctly. And then there is the identification of oddities and unknowns. A couple of years ago I found a periodic tone on a frequency, just a short tone every few seconds. A month or so later I found another tone, different duration, tone period, and frequency. After that I found a couple more, each of different lengths and periods. At first glance in the log they are unrelated, no correlation in times of day, pulse durations, pulse repetition periods, or basic frequency. However looking closer at the frequency revealed that each frequency was 67 Hz high, making a good possibility that they are all related in some way, possibly from the same transmitter.

So yes, there are times that great frequency accuracy, real accuracy, not just a lot of digits on the readout, is of use. Does the average BC SWL need it? Probably not, however it does not hurt at all to have the capability. And there are certainly types of monitoring that can benefit from high resolution frequency reporting.

T!
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Old 07-15-2014, 11:47 PM
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Tough crowd.
For what it's worth, I thought your IP address line was awesome! LOL
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Old 07-16-2014, 2:44 PM
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For what it's worth, I thought your IP address line was awesome! LOL
Haha, thanks!
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Old 07-18-2014, 1:50 AM
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The position of the decimal point depends on the multiplier of course. 12.3400MHz = 12340.0kHz. Logging a broadcast station to any more than 5kHz increments is a waste of time - he knows his transmit frequency to much better accuracy than your receiver will indicate. There aren't many HF broadcast stations that are not on 5kHz increments, but some of the Central and South American stations do tend to have "offsets".
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Old 07-18-2014, 12:44 PM
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The position of the decimal point depends on the multiplier of course. 12.3400MHz = 12340.0kHz. Logging a broadcast station to any more than 5kHz increments is a waste of time - he knows his transmit frequency to much better accuracy than your receiver will indicate. There aren't many HF broadcast stations that are not on 5kHz increments, but some of the Central and South American stations do tend to have "offsets".

But the original poster was asking about the format having TWO decimal points in is, such as 12.340.000 or 12.340.00. And N5IMS probably hit it closest, this is not a real 吐ormat (particularly with only 2 decimal places to the right) as much as it is a result of how radio readouts look / work, and so sometimes people report what they see on the readout, instead of what the frequency 途eally is.

If I tune my Icom R75 or the R8500 to 6715 kHz the readout says 6.715.00, and that just is not right as a raw frequency, the operator has to know that to the left of the left decimal is MHz, between the decimals is kHz, and to the right of the right decimal is Hz, however only 100痴 and 10痴 Hz are shown in these examples. Radios that include the 1痴 Hz position are fewer, for example my Yaesu FT-2000 does not, but my FTdx-5000 does. A few years ago a radio that read out to 1痴 Hz was a rarity, but they are becoming more common. And with the advent of SDRs read outs to 1 Hz are very common, even if accuracy to 1 Hz is still unusual.

While most big SW broadcasters are pretty close to their desired frequency it is still fairly common for a SW BC station to be a few Hz to 10痴 of Hz off. This can sometimes aid identification under poor conditions. Other stations intentionally are 登ff the 0 or 5 kHz steps, and again being able to tell how much they are off can help. While stations off the 0 and 5 kHz points are a definite minority, there are dozens of them out there, and reporting a station such as Radio Symban as on 2365 or 2370 is just wrong, when it is on 2368.5 kHz. And for the situation of Myanmar Radio (in Burmese) on 7200.1 and VOIRI (in Indonesian) on 7200 kHz, someone who speaks neither language might have a hard time identifying either station, particularly with poor signals, but knowing the real frequency can help you narrow down the possibilities, and aid in identification. Or what about those stations that are normally right on freq, but suddenly show up off freq? That might be noteworthy and worth reporting to others.

Logging it for your own reception however you want is fine, but reporting it to other listeners a couple kHz off because 0 or 5 kHz is 堵ood enough can lead to confusion. But it is really up to the listener, if you are a casual listener, or primarily listen for the content, then sure, logging in 5 kHz steps for AM broadcast are all that is needed. For someone trying to DX that hard to get third world BC station, maybe using SSB mode to isolate QRM, then having the real frequency is a help. And away from SW BC listening, say Utilities, Hams, Numbers Stations, etc, accuracy in reporting is more important.

For my own part my logs (in the frequency column) typically show frequency accuracy for any type of stations to 0.1 kHz (100 Hz), rounded to the nearest 100 Hz, assuming I can tell it that accurately. When I think it worth noting, I throw the exact frequency in the comments section of the log.

T!
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