science

Parallel Logic Radio Interface

Parallel Logic Radio Interface is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Parallel Logic Radio Interface rather than just read about it. In short: PLRI (Parallel Logic Radio Interface) is a set of circuits of interest to radio amateurs Amateur Radio (hams). These circuits are fully compatible with IRLP (Internet Radio Linking Project).

Key takeaways

Parallel Logic Radio Interface belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Parallel Logic Radio Interface to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Parallel Logic Radio Interface from memory before moving on to harder problems.

Reference excerpt

PLRI (Parallel Logic Radio Interface) is a set of circuits of interest to radio amateurs Amateur Radio (hams). These circuits are fully compatible with IRLP (Internet Radio Linking Project). IRLP is trademarked by Dave Cameron. The circuit shown below is the Deluxe PLRI interface, and is used to connect a radio to a PC using a parallel port and sound card. This circuit is fully compatible with the Version 3 IRLP board, and can be used in place of an IRLP board. This circuit allows negative or positive COS from the radio, and also supports negative or positive PTT keying. This circuit can be home built for roughly $20 US.

This circuit can be used with several software packages, such as Asterisk, Allstar, app_rpt, IRLP, RtpDir, TheLinkBox, Echolink or as a repeater controller board under any of the supported Linux software packages.

History Development on the prototype interface began in 2008. All of the PLRI circuits are original designs by Kyle Yoksh, K0KN, and therefore not reverse-engineered from the IRLP board or elsewhere. The PLRI circuit has had three major revisions so far. Besides the interface shown here, there are also three other PLRI circuits. One is a multi-radio version that supports up to 5 radios to be controlled by a single parallel port, and also supports serial operation. One is an adapter to allow use of an IRLP board to be controlled by a serial port, and the other provides the AUX 1,2,3 outputs not found on early IRLP boards. All PLRI circuits can be found at http://www.qsl.net/k0kn/plri

Construction The PLRI circuits are designed to use discrete components and DIP socketed integrated circuits for several reasons. For one thing, these are commonly found in ham operator's "junk boxes". Also, discrete transistors are able to sink more current than the tiny surface-mount transistors. Special soldering iron and magnifying glass not required! The PLRI interface consists of a hardware DTMF decoder, PTT circuit, COS circuit, and 3 auxiliary outputs for use with external circuits. The DTMF decoder circuit uses a MT8870 integrated circuit and a HCF4081 AND-gate integrated circuit. The AND-gate is used to provide a pulsed output to the PC parallel port, rather than the latched output of the MT8870. Auxiliary outputs 1,2,3 are built with NPN/PNP transistor pairs for several reasons. All outputs are capable of active high or active low switching. Active high switching allows for maximum switching current, as the NPN transistor is also used to light the corresponding LED and switch the PNP transistor. The PLRI interface can be connected directly to the radio(s), or connected to a Rigblaster-type interface The latter method is preferred, as the PLRI interface contains no audio circuitry such as isolation transformers or bypass capacitors.

Other This project includes a set of electronic schematics of interest to radio amateurs (ham radio). These circuits are compatible with the IRLP voice-over-IP (VOIP) system, and can be used for Echolink, IRLP, Asterisk and D-STAR systems using the RtpDir or TheLinkBox software packages. As of 2011, the App_rpt package for Linux (also known as Asterisk) supports the parallel port for COS/PTT, and thus supports the PLRI board. The PRLI Deluxe Interface Circuit can be directly connected to the node radio(s), or connected to the node radio(s) via a standard Rigblaster-type radio interface.

See also Asterisk (PBX) Echolink Internet Radio Linking Project

References

Taylor, Jonathan K1RFD. (2004). VoIP: Internet Linking for Radio Amateurs. American Radio Relay League, Inc. ISBN 0-87259-926-4.

External links Allstar Radio VOIP network PLRI Circuits from K0KN Asterisk PBX IRLP Echolink

Illustrations

Parallel Logic Radio Interface illustration

Worked examples

Example 1 — a first encounter with Parallel Logic Radio Interface

Start with the simplest possible case. Write down what Parallel Logic Radio Interface claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parallel Logic Radio Interface before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parallel Logic Radio Interface ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parallel Logic Radio Interface

In research: Parallel Logic Radio Interface appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Parallel Logic Radio Interface in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Parallel Logic Radio Interface is common in secondary-school and first-year university syllabi. It links to neighbouring topics Digital amateur radio, so understanding it makes those chapters shorter.
In everyday life: Look for Parallel Logic Radio Interface outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Parallel Logic Radio Interface in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Parallel Logic Radio Interface means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Parallel Logic Radio Interface out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parallel Logic Radio Interface in simple terms?

PLRI (Parallel Logic Radio Interface) is a set of circuits of interest to radio amateurs Amateur Radio (hams). These circuits are fully compatible with IRLP (Internet Radio Linking Project).

Why does Parallel Logic Radio Interface matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parallel Logic Radio Interface?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parallel Logic Radio Interface.