low pass audio filter

Transmission Lines - Whenever you choose a coax feedline, the frequency of operation is a very important consideration. Over the operating bandwidth of the coax the VSWR is low, typically 1.2:1 or better. Insertion loss is also an important parameter. It is usually specified in dB/foot and is a linear relationship.

SWR: Maximum allowable VSWR - VSWR (voltage-standing-wave-ratio) represents the degree with which an antenna is "matched" to the system impedance. Most modern antennas do not require any tuning for optimum performance. VSWR is one of the easiest parameters to measure and VSWR meters are becoming very popular antenna installation tools

New HF antenna HB9ABX  ^{updated  pop} - A new, revolutionary design allows the construction of small HF antennas, which provide the same efficiency as large antennas. This antenna can be built for all HF bands, from 10 to 80 m.

Contest audio file - MP3 file recording a QSOs with SP5CKA and SN7N (SP7PS) in SP DX Contest 2001 on 40m (recorded by SP7PS)

Telewave - Telewave's innovative engineering produces the industry's toughest antenna systems. Yagi, Fiberglass Collinear, and Dipole models are available from 66-2500 MHz. Wattmeters, test equipment,rf power meters, duplexers, filters and cavities, transmitters combiners

About digital modes - The digital modes provide a wonderful opportunity for those of us who would like to work on the HF bands but find CW too difficult and SSB phone prohibitive because of interference problems. The digital modes are easy to set up and get operating, require low power and a narrow band.

Freeband EQSO Server Priority listing - Eqso server for eleven meter freebanders. Only freebanders are allowed by this eqso server, based in spain

CQ SSTV de KB4YZ - Amateur slow scan television and digital sstv by KB4YZ

Isotron antenna manulas - From this page you can download the following manuals, in Adobe Acrobat format .pdf, 40 Meter Isotron, 80 Meter Isotron

Win APRS - Automatic Position Reporting System windows program, allow monitoring of real time geographical information such as the position of vehicles, the status of weather, radio direction finding and more.

Smith Chart Software - SimSmith is a highly interactive, real time Smith chart graphing program. Circuits are constructed using drag-n-drop. Load files can be imported from the EZNEC and CocoaNEC antenna simulation software and from the AIM4170 and miniVNApro antenna analyzers. Circuits and load files can be of any size. Key Features: SimSmith is one of the few Smith chart packages which models transmission line losses. SimSmith also allows the description of circuit elements using algebraic equations. SimSmith has only one screen and allows the screen to be resized to increase workspace or readability.

WEaudio recorder - WEaudio was born as a program to record activity on VLF band, it can records audio file on HD as long as you want within prefixed pauses. It can starts record at the hour you want to monitor.

DSPBOX - 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.

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

CW Decoder  ^pop - This program allows CW operators to copy CW code with a computer. The decoded CW is displayed as text or can generate a side tone. There is a spectrum display of the audio with a sliding cursor to select a particular audio for decoding. The program also allows for keying a transmitter from the keyboard with full CW break-in operation.

eQSLMaster - eQSLMaster is a HAM radio program, that allow to perform various functions using the Electronic QSL Card Centre (eQSL.cc). With eQSLMaster users of the eQSL.cc system have the ability to upload an entire ADIF format log file (or single QSO) and have it deposited into eQSL central database using LogServices.

RigResident - RigResident is a small program for RIG control, which does allow to set and read data of connected tranceiver (frequency, mode etc). RigResident supports more than 70 TRX models from ICOM, KENWOOD, YAESU and Ten-Tec.

DNBTV - This experimental software will send pictures or slow video directly from your webcam through your soundcard. you will need a webcam capable of 160*120 24bit RGB.

TCube - TCUBE is a combination of a Spectrum Analyzer and a Two Tone Generator, with optional quadrature outputs. It can be used for measuring the intermodulation behavior of an audio circuit, and as a general purpose tool

RightMark - RightMark Audio Analyzer

SpectraScope - SpectraScope is a simple Windows interface program allowing your computer to view up to two audio waveforms in either the time or frequency domain. The program is a Windows soft panel operating as a dual channel oscilloscope and spectrum analyzer. The useful frequency of operation is 20 to 10,000 Hz in the time domain and 20 to 20,000 Hz in the frequency domain. The program uses the computer sound card to capture the audio input.

WD6CNF Voice keyer - Audio voice keyer Microphone input, speaker output Live microphone enable Record/play audio from twelve memories Display text of recorded audio Transmitter keyed via serial (com) port Loop (with variable delay) audio output

HamView - 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.

Audio spectrum analyzer  ^pop - Analyzes audio from 10 Hz to 20 kHz, input from microphone or wave file, Variable sample rates (8000 Hz, 11025 Hz, 22050 Hz, 44100 Hz) Variable transform sizes (1k, 2k, 4k, 8k) Upper and lower limits adjustable Continuous, averaged, peak hold

Kenwood to pc serial ports - Simple, low cost interface between Kenwood serial ports and contest logging programs by Bob Wolbert, K6XX