Figure 3 shows transmission errors on the first and last bit. No errors are made so the detector syndrome is “0”. Error Detection Fig.2 CRC-4 No Transmission Errors Fig.3 CRC-4 Transmission Errorsįigure 2 shows a simple static Simulink model with a CRC-4 code used to detect errors on a simple 2byte=16bit data frame. However, if errors occurred and were not able to be corrected, then a NAK is returned to the transmitter to indicate to resend the data frame. If an error(s) occurred and the FEC was able to correct it, then an ACK is also sent back. If a data frame is sent and received correctly, then an ACK is sent back to the transmitter to indicate the frame was received correctly and the next frame can be sent. CRC codes are used to detect whether errors have occurred. If the modem is sending critical data such as emails etc, then the overall transmission has to be error free. PSK31 for example is essentially keyboard to keyboard transmission with no error detection or correction. HF modems may or may not contain error detection and correction. HF Error Detection & Correction Fig.1 HF FEC Forward Error Correction & CRC Error Detection In this post I will focus on using FEC Forward Error Correction to improve the transmission performance. I introduced several channel models using Scicos: an 8 channel discrete model and a 64 channel model using IFFT/FFT. Pictures of Generating, Storing and Verifying the Mesh Data # G28 sent and machine is preheating.In previous posts I examined the possible use of OFDM for HF messaging (Ref. If you want to use ABL fading use M420 S1 Z10 – This will fade ABL compensation until it is off over the first 10mm of the print.Load your slicer and open up the settings where the starting code is stored.Update your slicer to use the stored mesh # You will need to run the steps above to generate a new mesh if you clear the EEPROM and/or update the firmware. NOTE: This mesh will be wiped out should you clear the EEPROM (M502) and/or if you update the firmware. Let the printer sit at temperature for 5 minutes to let everything expand as it heatsĪfter doing these steps the mesh is now stored in the printer EEPROM.Preheat the machine to your normal print temperature.Pictures are at the end of the article if you want to see how it should look. Every printer is different so your mileage may vary. Try it out and see if it works for your machine. If you have a machine that the gantry always gets out of level this may not work as well as probing a new mesh at the start of every print. To do this just repeat the steps below in the “Steps to generate and store the bed leveling mesh” section. If you notice the stored mesh is not working as well anymore then get a new mesh. Over time your bed may warp slightly differently or things can shift. NOTE: If you change your bed surface and/or remove the plate you are printing on you may need to get a new mesh. Read this entire article to get this setup. This will save print time as you won’t need to probe the bed every print. You can store this mesh in the printer EEPROM. What this means is that you only need to probe the bed initially and then you can store it so all that is needed in your starting code is G28 then M420 S1 to recall the mesh data from EEPROM. The EZABL and the Unified Firmware support storing your bed leveling mesh. The information on this page is provided as-is with no support or warranty from TH3D. Some people who have very stable and properly build machines can take advantage of a stored mesh to decrease print start times but it is not recommended on most printers. This guide is put together for people who asked but we always recommend running a fresh mesh (G29) before starting a print like our installation guide states. This is only for use by advanced users that have their EZABL system installed correctly and understand fully how it works.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |