PPI is a standard for link layer packet encapsulation, proposed as generic extensible container to store both captured in-band data and out-of-band data. Originally it was developed to provide 802.11n radio information, but can be used for other purposes as well.
Sample capture: https://wiki.wireshark.org/uploads/27707187aeb30df68e70c8fb9d614981/http.cap
This page hosts a formal specification of packet_ppi using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
use strict;
use warnings;
use IO::KaitaiStruct 0.009_000;
use EthernetFrame;
########################################################################
package PacketPpi;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
our $PFH_TYPE_RADIO_802_11_COMMON = 2;
our $PFH_TYPE_RADIO_802_11N_MAC_EXT = 3;
our $PFH_TYPE_RADIO_802_11N_MAC_PHY_EXT = 4;
our $PFH_TYPE_SPECTRUM_MAP = 5;
our $PFH_TYPE_PROCESS_INFO = 6;
our $PFH_TYPE_CAPTURE_INFO = 7;
our $LINKTYPE_NULL_LINKTYPE = 0;
our $LINKTYPE_ETHERNET = 1;
our $LINKTYPE_AX25 = 3;
our $LINKTYPE_IEEE802_5 = 6;
our $LINKTYPE_ARCNET_BSD = 7;
our $LINKTYPE_SLIP = 8;
our $LINKTYPE_PPP = 9;
our $LINKTYPE_FDDI = 10;
our $LINKTYPE_PPP_HDLC = 50;
our $LINKTYPE_PPP_ETHER = 51;
our $LINKTYPE_ATM_RFC1483 = 100;
our $LINKTYPE_RAW = 101;
our $LINKTYPE_C_HDLC = 104;
our $LINKTYPE_IEEE802_11 = 105;
our $LINKTYPE_FRELAY = 107;
our $LINKTYPE_LOOP = 108;
our $LINKTYPE_LINUX_SLL = 113;
our $LINKTYPE_LTALK = 114;
our $LINKTYPE_PFLOG = 117;
our $LINKTYPE_IEEE802_11_PRISM = 119;
our $LINKTYPE_IP_OVER_FC = 122;
our $LINKTYPE_SUNATM = 123;
our $LINKTYPE_IEEE802_11_RADIOTAP = 127;
our $LINKTYPE_ARCNET_LINUX = 129;
our $LINKTYPE_APPLE_IP_OVER_IEEE1394 = 138;
our $LINKTYPE_MTP2_WITH_PHDR = 139;
our $LINKTYPE_MTP2 = 140;
our $LINKTYPE_MTP3 = 141;
our $LINKTYPE_SCCP = 142;
our $LINKTYPE_DOCSIS = 143;
our $LINKTYPE_LINUX_IRDA = 144;
our $LINKTYPE_USER0 = 147;
our $LINKTYPE_USER1 = 148;
our $LINKTYPE_USER2 = 149;
our $LINKTYPE_USER3 = 150;
our $LINKTYPE_USER4 = 151;
our $LINKTYPE_USER5 = 152;
our $LINKTYPE_USER6 = 153;
our $LINKTYPE_USER7 = 154;
our $LINKTYPE_USER8 = 155;
our $LINKTYPE_USER9 = 156;
our $LINKTYPE_USER10 = 157;
our $LINKTYPE_USER11 = 158;
our $LINKTYPE_USER12 = 159;
our $LINKTYPE_USER13 = 160;
our $LINKTYPE_USER14 = 161;
our $LINKTYPE_USER15 = 162;
our $LINKTYPE_IEEE802_11_AVS = 163;
our $LINKTYPE_BACNET_MS_TP = 165;
our $LINKTYPE_PPP_PPPD = 166;
our $LINKTYPE_GPRS_LLC = 169;
our $LINKTYPE_GPF_T = 170;
our $LINKTYPE_GPF_F = 171;
our $LINKTYPE_LINUX_LAPD = 177;
our $LINKTYPE_BLUETOOTH_HCI_H4 = 187;
our $LINKTYPE_USB_LINUX = 189;
our $LINKTYPE_PPI = 192;
our $LINKTYPE_IEEE802_15_4 = 195;
our $LINKTYPE_SITA = 196;
our $LINKTYPE_ERF = 197;
our $LINKTYPE_BLUETOOTH_HCI_H4_WITH_PHDR = 201;
our $LINKTYPE_AX25_KISS = 202;
our $LINKTYPE_LAPD = 203;
our $LINKTYPE_PPP_WITH_DIR = 204;
our $LINKTYPE_C_HDLC_WITH_DIR = 205;
our $LINKTYPE_FRELAY_WITH_DIR = 206;
our $LINKTYPE_IPMB_LINUX = 209;
our $LINKTYPE_IEEE802_15_4_NONASK_PHY = 215;
our $LINKTYPE_USB_LINUX_MMAPPED = 220;
our $LINKTYPE_FC_2 = 224;
our $LINKTYPE_FC_2_WITH_FRAME_DELIMS = 225;
our $LINKTYPE_IPNET = 226;
our $LINKTYPE_CAN_SOCKETCAN = 227;
our $LINKTYPE_IPV4 = 228;
our $LINKTYPE_IPV6 = 229;
our $LINKTYPE_IEEE802_15_4_NOFCS = 230;
our $LINKTYPE_DBUS = 231;
our $LINKTYPE_DVB_CI = 235;
our $LINKTYPE_MUX27010 = 236;
our $LINKTYPE_STANAG_5066_D_PDU = 237;
our $LINKTYPE_NFLOG = 239;
our $LINKTYPE_NETANALYZER = 240;
our $LINKTYPE_NETANALYZER_TRANSPARENT = 241;
our $LINKTYPE_IPOIB = 242;
our $LINKTYPE_MPEG_2_TS = 243;
our $LINKTYPE_NG40 = 244;
our $LINKTYPE_NFC_LLCP = 245;
our $LINKTYPE_INFINIBAND = 247;
our $LINKTYPE_SCTP = 248;
our $LINKTYPE_USBPCAP = 249;
our $LINKTYPE_RTAC_SERIAL = 250;
our $LINKTYPE_BLUETOOTH_LE_LL = 251;
our $LINKTYPE_NETLINK = 253;
our $LINKTYPE_BLUETOOTH_LINUX_MONITOR = 254;
our $LINKTYPE_BLUETOOTH_BREDR_BB = 255;
our $LINKTYPE_BLUETOOTH_LE_LL_WITH_PHDR = 256;
our $LINKTYPE_PROFIBUS_DL = 257;
our $LINKTYPE_PKTAP = 258;
our $LINKTYPE_EPON = 259;
our $LINKTYPE_IPMI_HPM_2 = 260;
our $LINKTYPE_ZWAVE_R1_R2 = 261;
our $LINKTYPE_ZWAVE_R3 = 262;
our $LINKTYPE_WATTSTOPPER_DLM = 263;
our $LINKTYPE_ISO_14443 = 264;
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{header} = PacketPpi::PacketPpiHeader->new($self->{_io}, $self, $self->{_root});
$self->{_raw_fields} = $self->{_io}->read_bytes(($self->header()->pph_len() - 8));
my $io__raw_fields = IO::KaitaiStruct::Stream->new($self->{_raw_fields});
$self->{fields} = PacketPpi::PacketPpiFields->new($io__raw_fields, $self, $self->{_root});
my $_on = $self->header()->pph_dlt();
if ($_on == $PacketPpi::LINKTYPE_PPI) {
$self->{_raw_body} = $self->{_io}->read_bytes_full();
my $io__raw_body = IO::KaitaiStruct::Stream->new($self->{_raw_body});
$self->{body} = PacketPpi->new($io__raw_body);
}
elsif ($_on == $PacketPpi::LINKTYPE_ETHERNET) {
$self->{_raw_body} = $self->{_io}->read_bytes_full();
my $io__raw_body = IO::KaitaiStruct::Stream->new($self->{_raw_body});
$self->{body} = EthernetFrame->new($io__raw_body);
}
else {
$self->{body} = $self->{_io}->read_bytes_full();
}
}
sub header {
my ($self) = @_;
return $self->{header};
}
sub fields {
my ($self) = @_;
return $self->{fields};
}
sub body {
my ($self) = @_;
return $self->{body};
}
sub _raw_fields {
my ($self) = @_;
return $self->{_raw_fields};
}
sub _raw_body {
my ($self) = @_;
return $self->{_raw_body};
}
########################################################################
package PacketPpi::PacketPpiFields;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{entries} = ();
while (!$self->{_io}->is_eof()) {
push @{$self->{entries}}, PacketPpi::PacketPpiField->new($self->{_io}, $self, $self->{_root});
}
}
sub entries {
my ($self) = @_;
return $self->{entries};
}
########################################################################
package PacketPpi::Radio80211nMacExtBody;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{flags} = PacketPpi::MacFlags->new($self->{_io}, $self, $self->{_root});
$self->{a_mpdu_id} = $self->{_io}->read_u4le();
$self->{num_delimiters} = $self->{_io}->read_u1();
$self->{reserved} = $self->{_io}->read_bytes(3);
}
sub flags {
my ($self) = @_;
return $self->{flags};
}
sub a_mpdu_id {
my ($self) = @_;
return $self->{a_mpdu_id};
}
sub num_delimiters {
my ($self) = @_;
return $self->{num_delimiters};
}
sub reserved {
my ($self) = @_;
return $self->{reserved};
}
########################################################################
package PacketPpi::MacFlags;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{unused1} = $self->{_io}->read_bits_int_be(1);
$self->{aggregate_delimiter} = $self->{_io}->read_bits_int_be(1);
$self->{more_aggregates} = $self->{_io}->read_bits_int_be(1);
$self->{aggregate} = $self->{_io}->read_bits_int_be(1);
$self->{dup_rx} = $self->{_io}->read_bits_int_be(1);
$self->{rx_short_guard} = $self->{_io}->read_bits_int_be(1);
$self->{is_ht_40} = $self->{_io}->read_bits_int_be(1);
$self->{greenfield} = $self->{_io}->read_bits_int_be(1);
$self->{_io}->align_to_byte();
$self->{unused2} = $self->{_io}->read_bytes(3);
}
sub unused1 {
my ($self) = @_;
return $self->{unused1};
}
sub aggregate_delimiter {
my ($self) = @_;
return $self->{aggregate_delimiter};
}
sub more_aggregates {
my ($self) = @_;
return $self->{more_aggregates};
}
sub aggregate {
my ($self) = @_;
return $self->{aggregate};
}
sub dup_rx {
my ($self) = @_;
return $self->{dup_rx};
}
sub rx_short_guard {
my ($self) = @_;
return $self->{rx_short_guard};
}
sub is_ht_40 {
my ($self) = @_;
return $self->{is_ht_40};
}
sub greenfield {
my ($self) = @_;
return $self->{greenfield};
}
sub unused2 {
my ($self) = @_;
return $self->{unused2};
}
########################################################################
package PacketPpi::PacketPpiHeader;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{pph_version} = $self->{_io}->read_u1();
$self->{pph_flags} = $self->{_io}->read_u1();
$self->{pph_len} = $self->{_io}->read_u2le();
$self->{pph_dlt} = $self->{_io}->read_u4le();
}
sub pph_version {
my ($self) = @_;
return $self->{pph_version};
}
sub pph_flags {
my ($self) = @_;
return $self->{pph_flags};
}
sub pph_len {
my ($self) = @_;
return $self->{pph_len};
}
sub pph_dlt {
my ($self) = @_;
return $self->{pph_dlt};
}
########################################################################
package PacketPpi::Radio80211CommonBody;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{tsf_timer} = $self->{_io}->read_u8le();
$self->{flags} = $self->{_io}->read_u2le();
$self->{rate} = $self->{_io}->read_u2le();
$self->{channel_freq} = $self->{_io}->read_u2le();
$self->{channel_flags} = $self->{_io}->read_u2le();
$self->{fhss_hopset} = $self->{_io}->read_u1();
$self->{fhss_pattern} = $self->{_io}->read_u1();
$self->{dbm_antsignal} = $self->{_io}->read_s1();
$self->{dbm_antnoise} = $self->{_io}->read_s1();
}
sub tsf_timer {
my ($self) = @_;
return $self->{tsf_timer};
}
sub flags {
my ($self) = @_;
return $self->{flags};
}
sub rate {
my ($self) = @_;
return $self->{rate};
}
sub channel_freq {
my ($self) = @_;
return $self->{channel_freq};
}
sub channel_flags {
my ($self) = @_;
return $self->{channel_flags};
}
sub fhss_hopset {
my ($self) = @_;
return $self->{fhss_hopset};
}
sub fhss_pattern {
my ($self) = @_;
return $self->{fhss_pattern};
}
sub dbm_antsignal {
my ($self) = @_;
return $self->{dbm_antsignal};
}
sub dbm_antnoise {
my ($self) = @_;
return $self->{dbm_antnoise};
}
########################################################################
package PacketPpi::PacketPpiField;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{pfh_type} = $self->{_io}->read_u2le();
$self->{pfh_datalen} = $self->{_io}->read_u2le();
my $_on = $self->pfh_type();
if ($_on == $PacketPpi::PFH_TYPE_RADIO_802_11_COMMON) {
$self->{_raw_body} = $self->{_io}->read_bytes($self->pfh_datalen());
my $io__raw_body = IO::KaitaiStruct::Stream->new($self->{_raw_body});
$self->{body} = PacketPpi::Radio80211CommonBody->new($io__raw_body, $self, $self->{_root});
}
elsif ($_on == $PacketPpi::PFH_TYPE_RADIO_802_11N_MAC_EXT) {
$self->{_raw_body} = $self->{_io}->read_bytes($self->pfh_datalen());
my $io__raw_body = IO::KaitaiStruct::Stream->new($self->{_raw_body});
$self->{body} = PacketPpi::Radio80211nMacExtBody->new($io__raw_body, $self, $self->{_root});
}
elsif ($_on == $PacketPpi::PFH_TYPE_RADIO_802_11N_MAC_PHY_EXT) {
$self->{_raw_body} = $self->{_io}->read_bytes($self->pfh_datalen());
my $io__raw_body = IO::KaitaiStruct::Stream->new($self->{_raw_body});
$self->{body} = PacketPpi::Radio80211nMacPhyExtBody->new($io__raw_body, $self, $self->{_root});
}
else {
$self->{body} = $self->{_io}->read_bytes($self->pfh_datalen());
}
}
sub pfh_type {
my ($self) = @_;
return $self->{pfh_type};
}
sub pfh_datalen {
my ($self) = @_;
return $self->{pfh_datalen};
}
sub body {
my ($self) = @_;
return $self->{body};
}
sub _raw_body {
my ($self) = @_;
return $self->{_raw_body};
}
########################################################################
package PacketPpi::Radio80211nMacPhyExtBody;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{flags} = PacketPpi::MacFlags->new($self->{_io}, $self, $self->{_root});
$self->{a_mpdu_id} = $self->{_io}->read_u4le();
$self->{num_delimiters} = $self->{_io}->read_u1();
$self->{mcs} = $self->{_io}->read_u1();
$self->{num_streams} = $self->{_io}->read_u1();
$self->{rssi_combined} = $self->{_io}->read_u1();
$self->{rssi_ant_ctl} = ();
my $n_rssi_ant_ctl = 4;
for (my $i = 0; $i < $n_rssi_ant_ctl; $i++) {
push @{$self->{rssi_ant_ctl}}, $self->{_io}->read_u1();
}
$self->{rssi_ant_ext} = ();
my $n_rssi_ant_ext = 4;
for (my $i = 0; $i < $n_rssi_ant_ext; $i++) {
push @{$self->{rssi_ant_ext}}, $self->{_io}->read_u1();
}
$self->{ext_channel_freq} = $self->{_io}->read_u2le();
$self->{ext_channel_flags} = PacketPpi::Radio80211nMacPhyExtBody::ChannelFlags->new($self->{_io}, $self, $self->{_root});
$self->{rf_signal_noise} = ();
my $n_rf_signal_noise = 4;
for (my $i = 0; $i < $n_rf_signal_noise; $i++) {
push @{$self->{rf_signal_noise}}, PacketPpi::Radio80211nMacPhyExtBody::SignalNoise->new($self->{_io}, $self, $self->{_root});
}
$self->{evm} = ();
my $n_evm = 4;
for (my $i = 0; $i < $n_evm; $i++) {
push @{$self->{evm}}, $self->{_io}->read_u4le();
}
}
sub flags {
my ($self) = @_;
return $self->{flags};
}
sub a_mpdu_id {
my ($self) = @_;
return $self->{a_mpdu_id};
}
sub num_delimiters {
my ($self) = @_;
return $self->{num_delimiters};
}
sub mcs {
my ($self) = @_;
return $self->{mcs};
}
sub num_streams {
my ($self) = @_;
return $self->{num_streams};
}
sub rssi_combined {
my ($self) = @_;
return $self->{rssi_combined};
}
sub rssi_ant_ctl {
my ($self) = @_;
return $self->{rssi_ant_ctl};
}
sub rssi_ant_ext {
my ($self) = @_;
return $self->{rssi_ant_ext};
}
sub ext_channel_freq {
my ($self) = @_;
return $self->{ext_channel_freq};
}
sub ext_channel_flags {
my ($self) = @_;
return $self->{ext_channel_flags};
}
sub rf_signal_noise {
my ($self) = @_;
return $self->{rf_signal_noise};
}
sub evm {
my ($self) = @_;
return $self->{evm};
}
########################################################################
package PacketPpi::Radio80211nMacPhyExtBody::ChannelFlags;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{spectrum_2ghz} = $self->{_io}->read_bits_int_be(1);
$self->{ofdm} = $self->{_io}->read_bits_int_be(1);
$self->{cck} = $self->{_io}->read_bits_int_be(1);
$self->{turbo} = $self->{_io}->read_bits_int_be(1);
$self->{unused} = $self->{_io}->read_bits_int_be(8);
$self->{gfsk} = $self->{_io}->read_bits_int_be(1);
$self->{dyn_cck_ofdm} = $self->{_io}->read_bits_int_be(1);
$self->{only_passive_scan} = $self->{_io}->read_bits_int_be(1);
$self->{spectrum_5ghz} = $self->{_io}->read_bits_int_be(1);
}
sub spectrum_2ghz {
my ($self) = @_;
return $self->{spectrum_2ghz};
}
sub ofdm {
my ($self) = @_;
return $self->{ofdm};
}
sub cck {
my ($self) = @_;
return $self->{cck};
}
sub turbo {
my ($self) = @_;
return $self->{turbo};
}
sub unused {
my ($self) = @_;
return $self->{unused};
}
sub gfsk {
my ($self) = @_;
return $self->{gfsk};
}
sub dyn_cck_ofdm {
my ($self) = @_;
return $self->{dyn_cck_ofdm};
}
sub only_passive_scan {
my ($self) = @_;
return $self->{only_passive_scan};
}
sub spectrum_5ghz {
my ($self) = @_;
return $self->{spectrum_5ghz};
}
########################################################################
package PacketPpi::Radio80211nMacPhyExtBody::SignalNoise;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{signal} = $self->{_io}->read_s1();
$self->{noise} = $self->{_io}->read_s1();
}
sub signal {
my ($self) = @_;
return $self->{signal};
}
sub noise {
my ($self) = @_;
return $self->{noise};
}
1;