DIY project technique. Part one
We continue to sort out the methodology for implementing DIY projects presented in the introductory part of the article by the example of an amateur project that the author of the article performs. Description of the project activity is carried out using the methodology and terminology of GOST R 54869-2011 "Project Management. Requirements for project management." The description of the activities at the project planning stage for clarity is supplemented with some "industry specifics".
The project started on 01/01/2018 and is at the stage of draft design .
The purpose of the project: the popularization and development of amateur radio communications on short waves.
Minimally viable product of the project: a radio designer that is affordable for a high school student for self-assembly of a radio observer receiver ( SWL ).
The project budget is not approved, the cost of the project in 2018 amounted to 6481 rubles 42 kopecks.
Project schedule without specifying specific dates.
Background of the project
The idea of self-development of a simple modern amateur radio station for the first time visited me during the assembly of a new transceiver from ready-made modules of domestic development. It was nice to "touch" the signal processing technology that was new to me DDC / DUC, but the process was burdened by some incomprehensible "heavy legacy of the damned past": the source codes of the firmware were not published; module diagrams were published, but did not correspond to reality; get timely qualified advice was problematic. So there was a desire to make "everything as it should."
Project initiation process
Finally, I was strengthened in my thoughts about starting a project, when I once visited my former mentor’s radio club. The situation there, in my opinion, is quite curious: there is a collective radio station, and the children are not interested in the radio, and, by the way, to solder something, too! But at the same time, children are interested in robots and program something there ...
It was then that the project’s intention was finally formed:
- The project is developing a mainboard with a 2.4 ”TFT display, reminiscent of STM32F4DISCOVERY, but with controls (encoders, buttons) next to the display, as well as a frequency synthesizer and an I2S audio codec“ on board ”;
- the main board has the ability to connect to a computer as a USB audio device, as well as a USB COM port for controlling the card via a CAT interface;
- the display serves, in particular, to display a panoramic indicator;
- products based on the main board have a block-modular design: the main board of the device can be expanded with radio channel SDR ( Software-defined radio ) receiver, radio CB ( Civil Band ) radio station, radio SDR transceiver, etc.
- text, graphic and video materials of the project are published under the terms of the license CC BY-SA 3.0 ;
The software developed and adapted by the project is published under the terms of the GNU GPLv3 license .
There is nothing fundamentally new in the design of the project:
- the block-modular principle of radio station construction is described in detail in the book by Ya.S. Lapovka (UA1FA) “I am building a HF radio station” - M., DOSAAF, 1983;
- The mathematical signal processing apparatus used in SDR is described in Chapter 3, The Phase Method of Forming and Receiving SSB Signals, in the book by V.T. Polyakova (RA3AAE) "Direct Conversion Transceivers". - M., DOSAAF, 1984;
- An example of the implementation of the receiving path with a key mixer is given in the article of V.T. Polyakova “Synchronous AM Receiver” - “Radio”, 1984, No. 8, pp. 31-34.
The first two sources are lovingly kept in my bookcase as soon as 35 years old. Their photo is used as a KDPV. Despite the fact that the technical solutions described in these publications are outdated long ago, the ideas presented there are still relevant.
And one more thing: it was immediately clear that we would have to finance the project and manage the project independently.
Project Content Planning Process
An example of the implementation of a unique product of the project is the mcHF QRP TRX MXNKA transceiver. Scheme, drawings and source codes of the transceiver are in the public domain.
The M0NKA transceiver is a fully autonomous radio station: it has local controls, a color display with a panoramic indicator, and signal processing is performed by its own computational tools. The transceiver has the ability to connect to a computer as a USB audio device and a USB COM port. The command system of the CAT interface is similar to the command system of the popular YAESU FT-817 transceiver.
The promise of the M0NKA transceiver is confirmed, including by the fact that there is at least one alternative to open source firmware for it , and the fact that the Chinese industry produces several "clones" of this device:
As the minimum viable product of the project can be considered the implementation of the functionality of the following products:
- SoftRock Lite II RX receiver by KB9YIG (extremely minimal viable product);
- Transceiver Peaberry SDR V2 by AE9RB (just MVP).
Schemes, drawings and source codes of these products are in the public domain. And SoftRock Lite II RX, and Peaberry SDR V2 can be purchased, both assembled and in the form of sets for self-assembly.
Both developments do not have local controls and work as "attachments" to the computer. To control the operation and signal processing modes, as a rule, use the freeware HDSDR program :
The SoftRock Lite II RX receiver connects to the USB connector and the analog input of a computer sound card. The Peaberry SDR V2 transceiver connects only to USB, since Includes USB audio device. The control of the frequency setting and modes of operation of these devices, since they have no CAT interface, HDSDR is implemented using open source software developed by amateur radio operator from the Netherlands, PE0FKO.
As a result of the analysis of the existing solutions for the development of the mainboard MVP, the following element base was chosen: MCU STM32F103RET6, si5351B frequency synthesizer, TLV320AIC3105 codec, TFT display ILI9341 with SPI interface. The final choice of MCU was delayed until the results of the implementation of the USB audio device. Alternatively, the STM32F407 and STM32F429 are considered.
In the path of the MVP radio channel, a well-proven QSD (quadratic key detector) and QSE (quadratic key pathogen) transceiver of the Peaberry SDR V2 transceiver is used.
Project staff planning process
The time of solitary geniuses remains in the distant past. Today, projects are executed by the project team. Even in such a simple project as under consideration, competencies are needed:
- project manager;
- design engineer;
- circuit engineering;
- PCB tracer;
- software engineer.
My professional skills were enough in this list for everything except programming. I didn’t offer to programmers to work in my project for free. I decided to master the competence of a software engineer independently, and in the course of exchanging views with colleagues I received practical advice:
- do everything myself until I get a working prototype;
- develop STM32 programming skills on inexpensive ready-made debug boards like the Blue Pill ;
- to apply strictly certain software in development (if, of course, I want to receive consultations from colleagues).
Although I was still alone with the project, colleagues, nevertheless, often helped me out in word and deed.
Project procurement planning process
Since I had no experience with anything from the chosen element base, I got into the procurement plan:
- any small things within 1000 rubles;
- debug board NUCLEO-F103RB , with a recommended price of $ 10.32;
- debug board TLV320AIC3105EVM-K , with a suggested price of $ 99;
- debug board Si535X-B20QFN-EVB , with a recommended price of $ 150;
- logical analyzer Saleae Logic 8 , with a recommended price of $ 399;
- Digital oscilloscope Rigol DS-1102E , with a recommended price of $ 461.
After overcoming a psychological barrier by the procurement plan, $ 1000 decided to postpone procurement planning for a while and begin to plan risks.
Risk response planning process
A project risk is a probable event, the occurrence of which can both negatively and positively affect the project results. Risks document and rank them by probability and by degree of influence on the project.
Below is a completely non-canonical, simplest register of risks of the project under consideration. I didn’t analyze more deeply:
Event 1: A unique product of the project is designed and put into production. Probability: low. Response scenario: initially focus on industrial production, lay in the technical requirements of the parameters of the manufacturability of the product.
Event 2: The project is closed after successfully testing the MVP project. Probability: average. Response scenario: development in the course of the project implementation of working design (software) documentation in a volume sufficient for publication after the project is closed.
Event 3: The project is closed until the end of the MVP project development. Probability: high. Response scenario: initially focus on minimizing project costs.
Even from this simplest analysis it is obvious that the probability of successful completion of the project is small. As for the likelihood of return on investment in the project, it tends to zero. The conclusion from this is one: in any event in an amateur project, procurement must be minimized, and all work must be carried out independently.
Risk Procurement Plan
After analyzing the risk, the procurement plan in the project became more modest:
- Chinese debugging board STM32F103RET6 for 450 rubles;
- programmer ST-Link v.2 for 500 rubles;
- clone Saleae Logic 8 for 500 rubles;
- any small things for prototyping within 5,000 rubles.
Project Scheduling Process
The project schedule was very simple:
- Getting STM32 programming skills on the debug board.
- Debugging the work of local authorities (encoders, buttons, display).
- Debugging the work of the si5351B and the radio channel, the implementation of an extremely minimal product.
- Debugging of the CAT-interface, si5351B and radio channel.
- TLV320AIC3105 debugging, USB sound device debugging, MVP implementation.
The organization of work is aimed at progressive movement in the implementation of the MVP functional from simple to complex. Terms are absent in principle.
In conclusion of the first part of the article I want to say that the apparent redundancy in the description of the planning process was introduced to better reveal the features of this process in an amateur project. This approach to planning ensured cost reduction and streamlined the execution of works during the project implementation. Currently, the third point of the schedule is being fulfilled: the radio channel is already receiving a signal from the generator, optimization of the si5351B operation is underway. Project costs during the year amounted to 6481.42 rubles.
And yet, colleagues! Do not regard all the above as a dogma. This is just an attempt to describe the specific experience of planning an amateur project. I really hope that any assessment will be accompanied by a comment.
73! Before communication!