# Tag Info

15

First, I'd be sure it's actually the antenna picking up the noise, and not something else. If you don't have a balun on that dipole, probably your feedline is picking up all the noise in your house. Any other wires attached to your receiver can also make good noise antennas, especially the power cord, which is attached to your home's wiring, and coupled to ...

6

On digital modes (particularly PSK31) RSQ (Readability, Strength, and Quality) is usually used for signal reports, instead of RST (Readability, Strength, CW Tone). There is some interesting history and background information on the RSQ system available at psb-info.net a site dedicated to the RSQ signal report. R = RSQ Readability (Percent characters ...

6

I have read this too. I don't have personal data to back this up, but the reasoning I have read stated that local RFI (like household appliances) tended to be vertically polarized and hence more able to induce noise onto a vertical antenna than a horizontal one. I'll edit the answer when I find the references. Meanwhile there are a few really excellent ...

4

WWVB propagation does vary in amplitude. And its BPSK phase modulation makes it a bit tricky to lock to. But if you narrow the bandwidth enough, signal is most always above the noise. Here's an example plot of WWVB amplitude in a fringe area similar to Boston...left half is night-time while right half is day-time. Each sample is exactly one second long. ...

4

Here are some visual examples, corresponding to what you'd see receiving an analog TV transmission. I've picked an image with features of varying detail. Look for: the letters "IPI" individual jelly beans contrast between the beans, especially the darker ones that are very close in brightness reflections on the beans Here are sets of three images side-by-...

4

I live in Seoul, Korea, a city of 15 million, with lots of lights and electronics on late until 11pm. My vertical dipoles I have created are easily 1 to 3 s-units noisier than horizontal dipoles. Absolutely no contest. The vertically-polarized antennas transmit DX very well, however. I actually run two antennas -- horizontal for listening, and transmit. ...

2

Another approach would be nulling one signal (say: your neighbor's plasma TV) to allow other signals to come over. Devices known as "noise cancellers" or "phasers" do exactly this. Try searching videos demonstrating MFJ-1026, Quantum Phaser and Timwave ANC-4 to have an idea how they work. They have some constraints: a) they can only null one signal at a ...

2

The relative power is calculated by squaring magnitude of the complex baseband signal followed by averaging, which would basically lead to RMS value. To get an RMS value, you would need to then take the root of this result. That is, I understand your description as: $$\frac{1}{n} \left( x_1^2 + x_2^2 + \cdots + x_n^2 \right)$$ but RMS is: $$\sqrt{ \... 2 There is no standard preferred signal report for digital voice. At the moment it's best to provide the number, and then explain where you got that number from and perhaps provide additional information as needed so the recipient can understand the meaning of it. As digital voice codecs advance and as users seek to evaluate them a few key characteristics ... 1 FLDigi will calculate the SNR for a PSK31 signal based on the spectrum scope. 1 Apart from the American time signal stations on shortwave. There is also CHU the Canadian time signal from Ottawa on 3.330 MHz, 7.850 MHz, and 14.670 MHz using USB mode. 1 You should be able to pick up WWVB at 60 kHz, or WWV at 2.5, 5, 10, 15, and 20 MHz. Propagation should allow you to routinely receive at 60 kHz, 2.5 MHz, and 5 MHz most nights unless the ionosphere has been disturbed by an event such as a solar flare. That would likely be your most reliable propagation. During the day time you should be able to receive 15 ... 1 I'm guessing by crossed Yagi, you mean two Yagis with a 90 degree phase shift, creating a circularly polarized Yagi. A circularly polarized antenna does not get you any gain. If the other end is linearly polarized, then there's a -3dB loss. The benefit is the loss is same no matter the orientation -- horizontal, vertical, or something in between. If you ... 1 Phil's answer is sound from a technical perspective since there is not sufficient data to fully answer the question. From a more pragmatic perspective, if you wish to increase the 12 dB SINAD sensitivity of your receiving system, you should: Minimize feedline losses Increase the gain of your antenna Your required 5 dB improvement in sensitivity is usually ... 1 Your reasoning is correct: in principle, given identical bit rate and signal power, the BER for BPSK and QPSK are identical. The Wikipedia article on PSK puts it nicely. The author there points out that you can think of a QPSK signal as two BPSK signals in the same channel, since they are orthogonal (one is built from sines, the other from cosines). You ... 1 A decibel is a mathematical measurement of the change in the magnitude of a quantity. It uses a logarithmic scale so that a change of 10 db is an increase of 10 times, while a change of 20 db is an increase of 100 times. The formula for computing the change in decibels between the original power P_0 and the new power P is$$10 \log\left(\dfrac{P}{P_0}\...

1

If your transceiver has an S-meter, one "S" has 6dB. Is decibel small? In my sense, yes, dB is quite small: it is difficult to hear a change of 1-5dB in voice quality. A 5-10dB change is significant, 15dB or 18dB totally changes conditions. Few devices in the amateur market can measure a 1dB difference. But precise "bookkeeping" of the antenna system is ...

1

Vertical antennas are noisier on HF and below for three main reasons: At HF and below, vertical antennas have more ohmic losses than horizontal antennas (mainly ground losses). Any ohmic resistance produces white, thermal Johnson–Nyquist noise (QRN) which power is proportional to the square root of the resistance $\sqrt{R}$. Vertical antennas are often not ...

1

To lower the incoming noise on a dipole antenna, connect a ground wire to the coax fitting at the antenna base. Run it to a ground rod and enjoy hearing stations that were covered up before. This does not drop incoming signals it just gives noise that comes in the shack on the shielding portion of the coax a direct path to ground. Turn off all filters and ...

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