Download
Share
Print this page
  1. Manuals
  2. Brands
  3. ELECRAFT Manuals
  4. Water Filtration Systems
  5. KDSP2
  6. Assembly and operating instructions manual

ELECRAFT KDSP2 Assembly And Operating Instructions Manual

Internal dsp filter and real-time clock
Hide thumbs

Advertisement

Quick Links

Download this manual
INTERNAL DSP FILTER and REAL-TIME CLOCK
Revision A.1, June, 2003.
Introduction
The KDSP2 DSP Filter is designed specifically for internal operation with an Elecraft K2 transceiver.
For the CW operator
The KDSP2 provides filter bandwidths from 50 to 800 Hz, with center frequencies from 400 Hz to 1,300
Hz, to help eliminate nearby interfering signals. The filters may be easily adjusted from the front panel,
and up to four (4) filters may be selected by the AFIL button.
Noise reduction helps reduce QRN, and may be used with any of the CW filters.
For the SSB operator
A tunable bandpass filter is settable from the front panel, offering low-frequency cutoff (high pass filter
function) from a few tens of Hz to 600 Hz, and a high frequency cutoff (low pass filter function) from 1.6
kHz to 3.0 kHz.
In addition to the tunable bandpass filter, an automatic notch filter quickly locates and suppresses
interfering carriers, such as those caused by other stations tuning up nearby. Noise reduction is also
available and may be used in conjunction with the bandpass and autonotch filters.
For the Data operator
Bandpass filters tuned for common HF data modes, such as RTTY, Packet and PSK31 are provided.
Center frequencies vary from 1 to 2.5 kHz, and widths from 50 Hz to 1 kHz.
Noise reduction and notch filters are not available in data modes as phase distortion may result in poor
copy on an otherwise clean-sounding signal.
Convenience Features
All filters are adjustable from the front panel. Up to four (4) filters per mode (CW/SSB/DATA) may be
memorized. The filters are then selected by simply pressing the AFIL button. A front-panel selectable
bypass mode is available which significantly reduces current consumption.
E
LECRAFT
Assembly and Operating Instructions
Copyright © 2003, Elecraft; All Rights Reserved
Elecraft
•
www.elecraft.com
KDSP2
•
831-662-8345

Advertisement

loading

Related Manuals for ELECRAFT KDSP2

Summary of Contents for ELECRAFT KDSP2

  • Page 1 The KDSP2 DSP Filter is designed specifically for internal operation with an Elecraft K2 transceiver. For the CW operator The KDSP2 provides filter bandwidths from 50 to 800 Hz, with center frequencies from 400 Hz to 1,300 Hz, to help eliminate nearby interfering signals. The filters may be easily adjusted from the front panel, and up to four (4) filters may be selected by the AFIL button.

  • Page 2: Specifications

    The main microcontroller firmware in the K2 must be version 2.01 or later. If you have an earlier version, contact Elecraft for an update. You can install the firmware upgrade during assembly of the KDSP2, but we recommend you install it ahead of time and verify correct operation of your K2 before you build and install the KDSP2.
  • Page 3 Assembly Parts Inventory Please check the enclosed parts with this list. Check off each item in the space provided. The number following the check-off space is the quantity required. The part numbers referenced are not necessarily marked on the parts. Rather, they are provided for reference when ordering replacement parts. Parts Sorting As you sort the parts, you may find it convenient to place them in a compartmented container for ready access.
  • Page 4 Capacitors Reference Value Type Marking Part Number 33 pF Ceramic Monolithic 33 or 330 E530144 470 pF Ceramic Monolithic E530080 C7, C9, C13 0.01 uF Ceramic Monolithic E530019 C3,-5, C8 0.1 uF Ceramic Monolithic E530020 C11, C15 0.33 uF Film 330n or 334 E530145 C10, C14...
  • Page 5 Part Number ATmega8L ATMEGA8L E610015 LM340T-5.0 LM340, 7805 E600024 NJU6355ED NJU6355 E600038 Note that U3 is pre-programmed with the KDSP2 application code. Hardware Description Part Number 4-40x1/4” Philips pan head screw E700005 4-40x0.5” Aluminum hex male-female threaded spacer E700057 Miscellaneous Reference...
  • Page 6 You should pre-bend the leads of resistors close to the body and at right angles. Quarter-watt resistor locations on the PCB have 0.35” centers (9mm). Near the upper left hand corner of the PCB: R1 10K ohm ¼ watt 5% carbon film resistor (brown-black-orange-gold) R2 10K ohm ¼...
  • Page 7 R16 2.2K ohm ¼ watt 5% carbon film resistor (red-red-red-gold) R13 220 ohm ¼ watt 5% carbon film resistor (red-red-brown-gold) R14 1M ohm ¼ watt 5% carbon film resistor (brown-black-green-gold) R17 470 ohm ¼ watt 5% carbon film resistor (yellow-violet-brown-gold) R18 470 ohm ¼...
  • Page 8 The reason for soldering is to relieve mechanical stress from the leads of U2 when the KDSP2 PCB is mounted and the mounting screw tightened The following capacitors are ceramic monolithic with radial leads. The capacitor should sit flush to the...
  • Page 9 Starting near the center left hand side of the PCB: C5 0.1 uF (104) C8 0.1 uF (104) C3 0.1 uF (104) C4 0.1 uF (104) Starting near the lower left hand side of the PCB: C12 (skip for now) C9 0.01 uF (103) C13 0.01 uF (103) C6 33 pF (33 or 330 - NOT the large, rectangular capacitor that may be marked 330n)
  • Page 10 PCB, with the top of the case not more than 0.375” (3/8” or 9.5mm) above the PCB. This is to provide clearance for the DSPx module which will sit above the KDSP2 PCB assembly. These parts all look very similar, but there are three different part types. You will first install the two parts that are different than the others.
  • Page 11 Z1 4.0 MHz (4, 4.0 or 4.00) U1 is the microcontroller that operates the KDSP2. It is socketed, and you will next install the socket. Be sure the socket pins are all through the PCB before you solder, as it is easy to bend one or fold one or more.
  • Page 12 Near U3 is a small, cylindrical crystal. The exposed lead length should be about 0.1” (2.5 mm). Be careful with the crystal’s leads, as they are very thin and may break if stressed. Do not attempt to push the crystal down flush to the PC board! Y1 32.768 kHz crystal As long as we are on the right side of the PCB, this is a good time to install the LED.
  • Page 13 When you install the IC in the next step, be very careful to not damage crystal Y1! Install U1 (ATMEGA8L) into the 28-in IC socket on the KDSP2 PCB. Be sure pin 1 (the end with a notch, dimple, or U-shaped pattern) is towards 20-pin connector J1 of the KDSP2.
  • Page 14 NOTE: The short end of the pins on the male headers are soldered into the KDSP2 PCB. On the bottom of the PCB at the now-right hand side: P1 5-pin male header (1 row of 5 pins) P2 3-pin male header (1 row of 3 pins) On the top of the board, install the final two capacitors.
  • Page 15 Control Board Preparation The control board of the K2 may need to be modified to accept the KDSP2. If you already have a KAF2, no further changes are required and you may skip this section and proceed to Installation. Verify the firmware on the Control board is at least rev 2.01. If it is earlier, contact Elecraft and obtain current firmware.

  • Page 16: Installation

    Ensure that the pins going into J1 and J2 are aligned properly. Misalignment (being off by one or more pins in either direction) may result in damage to the K2, the KDSP2, or both. If the mounting hole in the KDSP2 does not line up with the threaded hole in the spacer just installed, you may have the KDSP2 improperly mated with J1 and J2.
  • Page 17 Ensure the KDSP2 is completely seated on its connectors, and that it is properly aligned. Failure to align it properly could result in damage to the KDSP2, the DSPx, or both. When installed, there is a gap of about 1/16” (1 to 2 mm) between the KDSP2 and the bodies of the Control Board connectors. There are no mechanical fasteners to hold the DSPx in place.

  • Page 18: Initial Checkout

    KDSP2 controller. It is turned off when the DSPx receives a valid command from the KDSP2. This occurs within a second or so after power up, after the K2 announces its mode settings to the KDSP2.
  • Page 19 3-Volt Lithium Cell Installation Turn the K2 off. The (+) side of the 3-volt cell must be oriented towards the DSPx module. The (-) side must face the left side panel of the K2. DO NOT use long-nose pliers to hold the Lithium cell! Doing so will short the + and - sides together.

  • Page 20: Final Assembly

    (e.g., mobile installation in your off-road vehicle or helicopter). The black self-adhesive foam will be used to prevent the DSPx from disengaging from the KDSP2. Place the K2 top cover on a soft cloth or other clean surface to protect the painted finish on the cover.
  • Page 21 Don’t rotate it down into place as this may tend to compress or distort the foam. When properly installed, the foam will be just behind the DSPx module, preventing it from disengaging from the KDSP2. K2/100 On the forward edge of the heatsink, centered on the speaker, you will install the gray foam. This is ¼”...
  • Page 22 Attach the foam to the heatsink. We recommend you not leave the frequency counter cable installed in your K2/100. When you re-install KPA100 assembly on your K2/100, we recommend you place it down, then slide it forward. Don’t rotate it down into place as this may tend to tear or wedge the foam. When properly installed, the foam will be under slight compression, preventing the DSPx module from contacting the heatsink.
  • Page 23 You can use this to reduce the number of filters in a given mode’s sequence. On power up, the KDSP2 will default to the first filter for each mode. It will retain the current filter for each mode until power is again cycled.
  • Page 24 K2 display. For example, when going from CW filter 1 to CW filter 2, the display will briefly show: To display the KDSP2’s primary menu, tap the D I S PLAY button. KDSP2 Primary Menu In SSB or CW modes, the primary menu is used for the auto-notch and noise reduction functions. In RTTY, the primary menu is the Filters menu, described below.
  • Page 25 To toggle the denoiser, tap the BAND+ button. S2 .n1 nt appears for a second. The “1” signifies the current noise reduction level. This display will be followed by S2 .nr nt The decimal point preceding the nr indicates the denoiser is active. You will likely hear the difference in the noise level coming from the K2.
  • Page 26 The next menu after the main menu is the Filter menu. The Filter menu is the primary menu for RTTY mode. You can exit this menu, and all other KDSP2 menus, by turning the VFO knob, changing mode or filter, keying the radio, tapping D IS P LA Y , or holding X F IL .
  • Page 27 NOTE: the frequencies are always displayed as kHz with the decimal point in the appropriate place. NOTE: when the KDSP2 is taking over the K2 display for its various menus, the display updates once per second. During the update process, you may hear a brief noise in the audio. This is due to auxbus traffic within the K2, and is normal.
  • Page 28 You will be advanced to the Bypass Menu. It looks like this: dsp 0n You have the capability of bypassing the KDSP2 functions, which significantly reduces the power consumption of the KDSP2. If you tap BAND- , you will hear a change in audio and you will see...
  • Page 29 DSP BYPASS modes. This is normal. It is a result of muting the audio briefly to allow the audio levels to stabilize in the KDSP2. Otherwise, you might hear an annoying “pop.” You may also reach the Bypass menu from the K2 RTTY mode. The RTTY mode is enabled by a K2 secondary menu in version 2.x firmware and later.
  • Page 30 Gain Menus There are five Gain Menus available in the KDSP2. Their purpose is to allow you to balance the gain of the system for the types of signals you most listen to. Three of the menus are based on mode (CW, SSB or RTTY) and two are related to the Denoiser function.
  • Page 31 Gain menu or the Main menu for the current mode. Pressing the STORE button will display the firmware versions of the KDSP2 (see below) followed by the main menu for the current mode. The Gain menus available, by mode are:...
  • Page 32 KDSP2 microcontroller firmware version. In this example, it is 3.00. If the MCU firmware is prior to version 3.00, you will be returned to the KDSP2 main menu two seconds later. If the MCU firmware version is 3.00 or later, then after another two seconds you will see a Flash memory checksum...
  • Page 33 Ee.ee.ee ee-ee-ee This means the cell voltage is low. When you first construct the KDSP2, or after replacing the cell, this display will also be seen. Simply follow the clock and calendar setting procedure to erase the E’s. If the cell voltage is low, the cell needs to be replaced.
  • Page 34 Adjust the year by tapping BAND + to increase or BAND- to decrease. The display will wrap around between 99 and 00. To adjust the month, press RC L Adjust the month by tapping BAND + to increase or BAND- to decrease. The display will wrap around between 12 and 01.
  • Page 35 Menus Summary Mode Current Menu Next Menu Main Filter Filter Bypass Bypass Main Main Filter Filter Bypass Bypass Main RTTY Filter Bypass Bypass Filter Table 2 - Primary Menu Sequences Menu BAND+ BAND- STORE Main* Toggle Denoiser Toggle Autonotch** Next Menu *** Decrease Denoiser Level Filter*...
  • Page 36 Mode Current Menu Next Menu Time Calendar Format Calendar Format Year Year Month Month Date Date Hour Hour Minute Minute Time Bypass Time Time Table 4 - Real-Time Clock Menu Sequence Menu BAND + BAND- S TO RE Time Calendar Menu Calendar Menu Calendar Format** DSP Main Menu*...
  • Page 37 Table 1 from the beginning of this section is repeated here for the factory default filter settings. Mode Filter Center Width Notch Denoise Denoise Level Not avail PASS PASS 600 Hz 800 Hz Not avail 600 Hz 250 Hz Not avail 600 Hz 100 Hz Not avail...

  • Page 38: Troubleshooting

    Weak or no audio at some filter settings. If the KDSP2 filter is set to a frequency outside the XFIL range of the K2, it is normal for little or no audio to be heard. Be sure your XFIL setting and BFO frequency are such that audio will be present in the selected KDSP2 filter setting.
  • Page 39 Check U1, D3 and verify that the DSPx module is properly aligned and fully seated into its two connectors on the KDSP2 module. It is easy to be off by one pin in the alignment of these connectors. Also make sure that both rows of pins are inserted into J1.
  • Page 40 DC Voltage Chart Voltages are approximate. Measurements were made under the following conditions: 13.8 VDC power supply. K2 turned ON, 3V Lithium cell installed, CW mode with default CF1 filter setting (800 Hz center, 600 Hz wide, noise reduction OFF), display showing frequency, DSPx module removed. KNB2 and KSB2 options installed.

  • Page 41: Theory Of Operation

    The DSP process flow is shown above. Incoming signals are digitized at a 16 kHz rate. The samples are then decimated, a process to provide higher performance filters with fewer coefficients. In the KDSP2, decimation by 2 is performed, limiting the highest frequency to a little under 4 kHz.

  • Page 42: Circuit Description

    Circuit Description The KDSP2 is an interface board that adapts the DSPx Module for internal operation in an Elecraft K2 Transceiver. Please refer to the schematic for the following discussion. KDSP2 Audio Path Differential audio from the K2 Product Detector is supplied to the KDSP2 via 5-pin connector P1, pins 1 and 2.
  • Page 43 OFF, or high-impedance, state. If the KDSP2 needs to assert an auxbus level of HIGH, it turns on Q1, which turns on Q2 and pulls R7 to +5 VDC. This high level is passed through R6 and R7 to the auxbus.
  • Page 44 Real-Time Clock U3 is a real-time clock chip, incorporating clock and calendar functions. Y1 establishes the oscillator frequency of 32.768 kHz, with C6 to act as a fine adjustment. U1 communicates with U3 over a 4-wire serial bus. This is used to set the time and date, and read them back.
  • Page 45 Analog to Digital Converter. This is a device which accepts an analog signal and converts it to a digital value. In the KDSP2, the ADC accepts the signal from the K2 product detector and converts it to a 16-bit digital value. It does this 16,000 times per second.
  • Page 46 It is sometimes advantageous to reduce the sampling rate of a signal that has already been sampled. The process of doing this is called decimation. In the KDSP2, the input sampling rate is 16 kHz. The filters operate better with a sampling rate of 8 kHz. A “decimation by two” operation takes place to change the sampling rate to 8 kHz from 16 kHz.
  • Page 47 This is a process where a signal that was sampled at a lower rate is made to appear as if it were sampled at a higher rate. In the KDSP2, the autonotch and denoiser operate at a 16 kHz rate, but the filter that precedes them is running at 8 kHz.
  • Page 48 KDSP2 are the autonotch and the denoiser. Sampling When signals are digitized, they are said to be sampled. In the KDSP2, analog signals from the K2 product detector are sampled at a 16 kHz rate. This means that 16,000 times per second, the output voltage from the product detector is converted to a 16-bit digital value by the ADC and fed to the DSP.