Designing antenna arrays with adjustable beam width, azimuth, and elevation angles.
by Jim Lux, w6rmk
by Jim Lux, w6rmk
More information from Apple: https://support.apple.com/en-us/HT202663
A simple antenna tuner made from switches. How to determine the “best” transmission line lengths for multi-band center fed wire dipoles.
by Cecil Moore, W5DXP
By @F5OEOEvariste (article at: rtl-sdr.com)
http://www.rtl-sdr.com/transmitting-fm-am-ssb-sstv-and-fsq-with-just-a-raspberry-pi/
Send a CQ and immediately get a list of reverse beacon stations that heard your call, from around the world, with time and signal report data.
Logs are collected in a database that is accessible for research.
With a TenTec Eagle transceiver, Managed by N4PY software.
N4PY acts as router, distributing CAT commands to other applications.
The applications are connected using virtual serial port bridge pairs. For each of the applications, N4PY emulates a K3 transceiver on one side of the bridge.
The CW keyer is a K1EL Winkeyer USB controlled solely by the N1MM logger.
The routing of IQ signals from LP-PAN2 SDR is done through a MOTU 828 mk3 interface, simply to be able to split the signal so that both NAP3 and CW Skimmer can use it.
CW Skimmer gets the IQ signal directly from the MOTU. NAP3 doesn’t not recognize multiple ports on soundcards. So one end of the split from the MOTU is sent through another audio interface (Focusrite 2I2). NAP3 uses the 2I2 as an input device.
Notes on configuration for correct zero-beating.
When setting the Eagle BW or PBT, the IF will shift in frequency, so the numbers below assume a centered PBT and a BW of 700.
The sidetone pitch is 523 Hz.
Settings may also depend on which roofing filters are installed in the Eagle.
Set the global offset to -8200. Leave everything else at 0.
This post is about ham radio.
under construction…
Max/MSP features a full implementation of SQLite using the js (javascript) object. Here we describe a database to track radio frequencies. Frequencies are stored by time, type, and mode. The frequencies can be retrieved in various ways, like with a scanner radio.
Tables can be created and maintained outside of Max using the command line (sqlite3) or database apps like SQLiteStudio.
(not yet available on github:
The database is called newtestDB1
You can see the table schema in the screenshots. The tables were created using command line sqlite3 and SQLiteStudio.
One record for each stored frequency. This table retains its state from each previous use, but new records can be added using the Max patch, or the Launchpad.
xtime: Timestamp in UTC.
frequency: Hz.
mode:
filter: bandpass filter setting in Hz. (default is 6000)
typecodes:
0 : unknown
1 : AM/SW broadcast
2 : clock
3 : digital mode
4 : local broadcast
5 : mostly noise
zone: cq zone number
rating: 0-5 (0 = unrated)
confidence: 0-5 (0 = unknown)
tags: (general text notes)
The preset table contains one record for each 8×8 launchpad button, for each of 3 screens.
Data from each of theses screens is also displayed in jit.cellblock objects in the Max patch. All of the fields correspond to the fields in the freq table – except for screen, row, and col which are locators for the launchpad.
There are three screens of presets color coded using the Launchpad mixer button (upper right). Press it to cycle through the 3 screens.
The fixed presets are static. But can be changed using SQLiteStudio. They contain commonly used radio frequencies, like the SW, Ham, and CB bands. And clock stations.
To select a preset, press its button on the Launchpad.
Currently assigned presets:
Time presets are frequencies with Timestamps that match a selected range. For example, every frequency within one hour of the current time. These can be selected with a query in the Max patch, or using default values from the Launchpad. The query will randomly match up to 64 records. If the query returns less than 64 records, you will get all matching records, but in random order.
From the Max patch:
Match hours plus/minus current time (0-12).
Type the number of hours in the number box and press the button under the delay object. This reloads the presets.
You can view the results in the jit.cellblock:
Match a specific time range:
Enter the start/end times and press the button.
Selecting from launchpad
trk button: re-runs query using last set number of hours plus/minus current time. Default is one.
solo button: select one random preset using current hour range, and play it?
The user presets work like the pushbuttons on a car radio. Press to select. Hold to save the currently tuned radio frequency.
The learn button (upper left) gives feedback. If you press a pad for which no frequency has been assigned, the learn button will flash red. When you save a new preset, the learn button flashes green to indicated that the saving is done. If you press a pad for a preset that has already been saved, there will be no flash, but the radio frequency will change.
You can add records using the Max patch or the Launchpad, or from SQLiteStudio.
Tunning the radio fills in all of the fields except for typecode. Tune the radio. Then press one of the typecode buttons. Then press the big green button. You have added a new record.
Press the Arm button (lower right) to add a record for the currently tuned frequency, using an ‘unknown typecode’
Just do it.
How to set up the client side of the remote radio system.
(under construction) patches have not been uploaded to github
This client works with the sever described in the previous post. We are running a MacBook Pro OSx 10.11.4. with the following:
Install and set up LogMein Hamachi. It is free, for a limited number of computers. Set up a Hamachi server on both the server and client. It should look something like this:
We are using Soundjack VOIP. It is also free. Use the following parameters on the client side.
You can ignore the rest of the settings, since we are not sending audio. Most of the configuration is done on the server side.
Max
We are using several patches, depending on which hardware controllers you are using. Make sure that the hardware controllers are connected before opening Max.
After the max patches are loaded, you should be able to control the radio using the UI and the CDJ-101 controller. The red Mixer button in the upper right corner of the Launchpad should be lit.
to be continued…