Update vhf-acars.md

vhf-acars.md

@@ -23,16 +23,15 @@ Another option (I hear good things about but not tried) is the [sirio](https://w
 Here is an example of what NOT to buy. This airband antenna is BROKEN! [Amazon](https://www.amazon.com/dp/B07XNKX18D?ref_=cm_sw_r_ud_dp_QW7K7EJXCSYNG1BKXQTY)    
 Note that you can NOT use your existing ADSB one, the frequencies are not even close.  
 * 1 x coax cable, length for your installation. The good thing here is the frequency of ACARS is much lower than ADSB, so the coax loss is much lower. 
-A good starter is [RG-8x](https://www.amazon.com/s?k=rg-8x&crid=3QO4RHETIF7KL&sprefix=rg-%2Caps%2C212&ref=nb_sb_ss_ts-doa-p_7_3), a bit more harder to work with is [RG-213](https://www.amazon.com/s?k=rg-213&crid=2LGFNZMSJ9TVW&sprefix=rg-213%2Caps%2C126&ref=nb_sb_noss_1). ADSBExchange sell a range of coax cable types and lengths [Store](https://store.adsbexchange.com/collections/all)     
- Since its receive only, you can use good quality 75 ohm cable if you like [Amazon](https://www.amazon.com/s?k=75+ohm+outdoor+coax+cable&ref=nb_sb_noss)    
+A good starter is [RG-8x](https://www.amazon.com/s?k=rg-8x&crid=3QO4RHETIF7KL&sprefix=rg-%2Caps%2C212&ref=nb_sb_ss_ts-doa-p_7_3), a bit more harder to work with is [RG-213](https://www.amazon.com/s?k=rg-213&crid=2LGFNZMSJ9TVW&sprefix=rg-213%2Caps%2C126&ref=nb_sb_noss_1). A lot of folks use [KMR240](https://www.amazon.com/gp/product/B09ZPCM98C) coax. Since its receive only, you can use good quality 75 ohm outdoor TV cable if you like [Amazon](https://www.amazon.com/s?k=75+ohm+outdoor+coax+cable&ref=nb_sb_noss). BTW, one of the reasons you can mix and match like this is because most SDRs are NOT 50 ohm input, they vary and its really not an issue.        
 * 1 x SMA splitter. You will need to split your antenna into 2 (or 3) SDRs if you plan to run both ACARS and VDL. [Amazon](https://www.amazon.com/Bingfu-Antenna-Splitter-Cellular-Amplifier/dp/B07STYNB6V/) This will get you started, if you need to split further, just look for the right combo of SMA male/female.    
 * 1 or 2 or 3 x SDR. [RTLSDRv3](https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/) or you can go for the [Orange ADSBEx](https://store.adsbexchange.com/products/adsbexchange-com-orange-r860-rtl2832u-0-5-ppm-tcxo-sdr-w-amp). Do NOT use the blue dongles, they are filtered for 1090Mhz ADSB and will not work on VHF-ACARS.   
  * 1 x Raspbery Pi. You can use your existing ADSB Pi (Check the CPU load first), or put in a new Pi.  
  * 1 x [USB Powered Hub](https://www.amazon.com/Anker-7-Port-Adapter-Charging-iPhone/dp/B014ZQ07NE/). If you end up using 3 ACARS dongles and your ADSB dongle (and perhaps a 978 dongle) on the same Pi, you will for sure need to run a powered hub.  
 
-Note, be very careful about running an LNA. ACARS is close to the FM band and you may overload the front of the SDR and make things worse. Look at your SDR waterfall software if you can to see what the RF interference in your area is like and see how well you are picking up the ACARS/VDL bursts.  
+Note, be very careful about running a VHF LNA. ACARS is close to the FM band and you may easily overload the RF front end of the SDR and make things worse. Look at your SDR waterfall software if you can to see what the RF interference in your area is like and see how well you are picking up the ACARS/VDL bursts. Most of the usual SDR software package have a waterfall feature where you can see a chunk of your frequency of interest.  
 I personally have had both success and failure running the [GPIO filtered airband LNA](https://gpio.com/products/airband-filtered-low-noise-amplifier?variant=19591697301526). In one location it was great and made a worthy addition, in another it made the signal useless. It was an expensive test. Your milage may vary.  
-## Serialize your SDRs      
+## Serialize your SDRs before you start      
 If you jump right in and install the software, you are going to get frustrated. The decoders start up as soon as they are installed and will grab the first open SDR it can find. This may or may not be the SDR you want. So how can we tell each decoder (even ADSB or UAT) to use the correct SDR connected to the correct antenna? By setting different serial numbers in each SDR dongle.   
 Because of course every SDR has the same serial number out of the box. Usually 000000000000000001 (I can never count how many zeros there are..... too many frankly) or if its an orange one it might have 978 or something else, and if its a blue one it might have 1090 or something else.   
 ### How to find your current serial numbers   
@@ -176,6 +175,7 @@ Here is an example of a config file for USA (frequencies will be different per l
 `DUMPVDL2_OPTIONS="--rtlsdr 1 --correction 2 --gain 32 --output decoded:json:udp:address=feed.airframes.io,port=5552 --station-id xxx-VDL2-yyyy 136650000 136800000 136975000"`   
 We are using USB device 1 here, use the rtl_test command to get the right one for your setup. I have a little PPM correction applied (+2). Gain set to 32. Feeding data to airframes and the three main frequencies in use here in USA (Some try and listen to more frequencies and only get overloaded duplicated messages with less main decodes since every added frequency reduces CPU and SDR/USB bandwidth for the real ones - ie, more is NOT better).   
 Change your station id to something sensible.    
+A few other config examples further down the page.
 
 ### Restart the service to apply changes   
 `sudo systemctl restart dumpvdl2`