Comparison of Beverage antenna
- A ranking of receiving antennas based on noise being evenly distributed in all directions. These rankings are most accurate in the frequency range of AM broadcast, 160 or 80 meter bands
Interference Cancelling System
- The use of interference signal cancellation has been around for some time. The idea is to use an auxiliary antenna almost any random length of wire in addition to the main receiving antenna
- PSK31 is a digital communications mode which is intended for live keyboard-to-keyboard conversations, similar to radioteletype. Its data rate is 31.25 bauds (about 50 word-per-minute), and its narrow bandwidth (approximately 60 Hz at -26 dB) reduces its susceptibility to noise.
VLF-LF And the Loop Aerial
- The article discusses the theory of loop aerials for receiving and how they reduce the level of local noise. A Loop Aerial is described suitable for use on the LF and VLF bands together with a circuit of an interface loop tuner and preamplifier. The discussion extends to the problems of amplifier noise and the advantages of tuning the loop.
[ Hits: 2858 | Votes: 5 | Rating: 5.40 ]
Antenna Noise and Signal Cancelling at LF
- The fact that the phasing between a wanted signal and an unwanted signal can be different on different antennas is put to advantage. With this condition, the unwanted signal can be cancelled out by controlling amplitude and phase. The heart of the system is some form of phase control circuitry.
KØBG's ham radio mobile operator web site
- This site is dedicated to mobile amateur radio operators, old and new alike. Whether you are into HF, or VHF operation, I trust the information presented will increase your enjoyment of our great hobby.
With safety as a byword, there are articles on amplifiers, antennas, bonding, impedance matching, installing hardware, mobile equipment, noise and RFI abatement, wiring, and much more. I do my best to keep these articles up to date, and easy to follow.
- DOS Freeware, DSPBOX is an attempt to code the Texas Instruments DSK 'C50 in such a way
to make it behave like a commercial DSP noise reduction unit, like the
NIR-12, the TimeWave 599+ and others. Not only the noise reduction function
has been implemented, but automatic notch, AGC and Band Pass have as well.
[ Hits: 1942 | Votes: 0 | Rating: 0.00 ]
WD6CNF DSP Filter
- Audio Digital Filter, two bandpass filters, three notch filters, two noise filters
graphical setting of filter center frequency and bandwidth Drag vertical lines on top of signal,
Microphone input, speaker output
Mono, 5 kHz bandwidth
- A freeware program to dig out weak signals buried in noise, functionally similar to the excellent FFTDSP of AF9Y, but with the added bonus of real time audio filtering of the incoming signals. Just point and click with the mouse, and the selected signal will stand out from the QRM and noise.
23 cm GaAs FET preamplifier
- On 23cm the best way to obtain a good RX-sensitivity is to use a GaAs-FET in the front-end, since these devices show very low noise figures.
[ Hits: 3425 | Votes: 5 | Rating: 5.20 ]
Receive only processing equipment
- One of our most popular products, receiving preamplifiers are used for achieving top signal band performance in competition operating, low noise longwave reception, repeater applications into the UHF region, or lab use
Antenna Noise and Signal Cancelling at LF
- By using the signals from two antennas, controlling their relative amplitudes and controlling the phase of one of them, unwanted signal or unwanted noise can be phased out. Circuitry is described which uses the signal from a wire antenna to provide selective cancelling against the signal output from an LF loop antenna.
[ Hits: 6809 | Votes: 3 | Rating: 6.00 ]
QRM and noise reductionPriority listing
- You will find on these pages my experiences and results on antennas and local/non-local QRM/noise reduction. Using a broadband vertical active magnetic loop and a home made / designed broadband amplifier. Two vertical magnetic Alford loops are used in an array.
Analog and Digital Signal Processing and a dual phase coherent Software Defined Radio (SDR) are used. By PA0SIM
[ Hits: 3964 | Votes: 4 | Rating: 8.00 ]
- Receiving Common Mode Noise shows how lack of a balun can contribute to system noise